Angiogenic and anti-angiogenic factors during the post-hatching growth of the quail (Coturnix coturnix japonica) spleen.

Vascular endothelial growth factor (VEGF) family members are responsible for endothelial cells' growth, proliferation, migration, angiogenesis, vascular permeability, and differentiation and proliferation of non-endothelial cell types. VEGF and its receptors are found in mammalian lymphoid organs. The present study was conceived to determine (a) the presence and localization of angiogenic VEGF and its receptors (Fms-like tyrosine kinase 1 [Flt1/fms], fetal liver kinase 1 [Flk1]/kinase insert domain receptor [KDR], Fms-like tyrosine kinase 4 [Flt4]) and vascular endothelial growth inhibitor (VEGI) in the quail spleen; and (b) whether their expressions in the spleen components change during the post-hatching growth of the organ, using immunohistochemistry. Immunohistochemical stainings showed that VEGI, VEGF, and VEGF receptors were expressed in many components, including the vascular endothelial and smooth muscle cells, ellipsoid-associated cells (EACs), and immune cells, of quail spleen and that VEGF and its receptors' immunostaining intensity scores (ISs) varied depending on the post-hatching growth period, while VEGI-IS did not change. In addition, ISs of VEGI, VEGF, Flt1/fms, and Flt4 in EACs were weak to moderate, while flk1/KDR-IS in EACs adjacent to the capsule of Schweigger-Seidel sheaths (ellipsoids) was higher than other proteins, supports a more important and specific role of Flk1/KDR in the EAC function. These specific expressions of VEGI, VEGF, flt1/fms, flk1/KDR, and flt4 proteins in splenic cell types suggest their particular roles, in the functional development of splenic components and thus, are critical to post-hatching maturation of quail spleen. These findings indicate that the expression levels of VEGF, Flt1/fms, and Flt4, except Flk1/KDR, are low in the quail spleen, and only a few components of the spleen express VEGF, Flt1/fms, and Flt4 under normal conditions.

Differential distribution of intermediate filament proteins in the bovine and ovine tongues.

Intermediate filaments constitute the most heterogeneous class among the major classes of cytoskeletal proteins of mammalian cells. The 40 or more intermediate filament proteins have been classified into five types which show very specific rules of expression in specialized cell types. This study aimed to investigate the immunohistochemical distribution of cytokeratins (CKs) 8, 18, and 19 as well as the intermediate filaments vimentin, laminin, and desmin in bovine and ovine tongues. Immunohistochemical staining was performed for CKs 8, 18, 19, vimentin, laminin, and desmin. Our results revealed similar immunostaining intensity and distribution among various CKs, contrasting with distinct patterns for vimentin, laminin, and desmin. Immunoreactions were primarily localized in serous acini and ductal epithelium for cytokeratins, while vimentin and laminin were evident in connective tissue, endothelium, serous acini, and desmin in striated and smooth muscles. This study highlighted the absence of CKs 8, 18, 19, vimentin, and desmin in the lingual epithelium of bovine and ovine tongues. These findings enabled the classification of epithelial cells based on their specific cytokeratin patterns. Furthermore, vimentin was identified in mesodermal tissues and organs, desmin in muscle tissue, and laminin played crucial roles in basement membrane formation, nerve tissue regeneration, innervation of epithelial taste buds, and tissue separation and connection. Our findings provide essential insights into intermediate filament dynamics at the cellular and tissue levels. They serve as a foundation for future studies using systematic molecular biological techniques in this field.

The immunolocalization of cadherins and beta-catenin in the cervix and vagina of cycling cows.

The adherens junctions (AJs) maintain the epithelial cell layers' structural integrity and barrier function. AJs also play a vital role in various biological and pathological processes. AJs perform these functions through the cadherin-catenin adhesion complex. This study investigated the presence, cell-specific localization, and temporal distribution of AJ components such as classical type I cadherins and beta-catenin in the cow cervix and vagina during the estrous cycle. Immunohistochemistry and Western blot analysis results demonstrated that beta-catenin and epithelial (E)-, neural (N)-, and placental (P)-cadherins are expressed in the cow cervix and vagina during the estrous cycle. These adhesion molecules were localized in the membrane and cytoplasm of the ciliated and non-ciliated cervical cells and the stratified vaginal epithelial cells. Positive immunostaining for P-, N-cadherin, and beta-catenin was also observed in the vascular endothelial cells of the cervical and vaginal stroma. Quantitative immunohistochemistry examinations revealed that in the cervical and vaginal epithelia, P-cadherin's optical density values (ODv) were the highest; in contrast, the N-cadherin ODv were the lowest. The ODv of P-cadherin and beta-catenin in the cervical epithelium and E-cadherin in the vagina were significantly higher in the luteal phase versus the follicular phase of the estrous cycle. Furthermore, the ODv of P-cadherin, N-cadherin, and beta-catenin in the cervix's central and peripheral epithelial regions were different during the estrous cycle. These findings indicate that classical cadherins and beta-catenin in the cervix and vagina exhibit cell- and tissue-specific expression patterns under the influence of estrogen and progesterone hormones during the estrous cycle.

Distribution of cytoskeletal proteins in the cat testis during the pre-pubertal and post-pubertal periods.

Cytoskeletal proteins not only define the shape of cells, but also have critical roles in their proliferation, migration and motility, as well as in the establishment and maintenance of tissue organization and integrity. Furthermore, these proteins influence the physiological processes of the male reproductive system and are found in the structure of some cells. This study aimed to determine differences between the pre- and post-pubertal periods for the localization and distribution of actin, desmin, vimentin and cytokeratin-18 in the testes, epididymides and ductus deferentes of Persian and Turkish Angora and Van cats, using immunohistochemistry. The study material was grouped as belonging to the pre-pubertal and post-pubertal periods. The tissue samples of both groups were subjected to routine histological processing and embedded in paraffin. Serial sections cut from the paraffin-embedded tissue blocks were immunohistochemically stained with the indirect streptavidin-biotin complex method. Immunohistochemical findings demonstrated that there was no difference between the pre- and post-pubertal periods for the staining intensity and distribution of the proteins actin, vimentin, desmin and cytokeratin-18 in Persian and Turkish Angora and Van cats. On the other hand, differences were detected between the pre- and post-pubertal periods for the cellular expression and localization of these proteins in the testes, epididymides and ductus deferentes. Thus, the study results suggest that, based on the expression of actin, desmin, vimentin and cytokeratin-18 in the testes, epididymides and ductus deferentes during both periods, these molecular factors could have a contributory role in the development of the male reproductive system and the regulation of its physiological processes.

Expression of cadherins and some connective tissue components in cow uterus and placenta during pregnancy.

The implantation and placental development processes are regulated with cell adhesion molecules and remodeling of the maternal endometrium's extracellular matrices (ECM) and fetal chorion. This study aimed to investigate the distribution and localization of some classical cadherins (E-, N-, and P-cadherins) and extracellular matrix components collagen type 5α1, fibronectin, and laminin in the cow placentomes during pregnancy using immunohistochemical and Western blotting analyses. The study results confirmed the expression of E- and P-cadherins, collagen type Vα1 (COLVα1), fibronectin, and laminin in the cow placentomes, but not N-cadherin. Throughout the pregnancy, E- and P- cadherins, COLVα1, and laminin were localized in the luminal and glandular epithelium of the inter-caruncular endometrium, caruncular epithelium, and the uninucleate (UNCs) and binucleate trophoblast giant cells (BNCs/TGCs). E- cadherin immunoreactivity in the first pregnancy period was strong in the UNCs while moderate in the BNCs/TGCs. However, it was weak in both trophoblast in the second and third pregnancy periods. In the fetal trophoblasts, P- cadherin and laminin immunostainings were more intense in the BNCs/TGCs than UNCs. The fetal and maternal stromal cells were also positive for P- cadherin, COLVα1, fibronectin, and laminin. The immunostaining intensity of COLVα1 and fibronectin in the stromal extracellular matrix of the placentomes decreased as the pregnancy progressed. The endothelia of fetal and maternal vessels were positive for all proteins. The presence and distinct localization of cadherins and ECM proteins in the cow placentome components support the role of these molecules in regulating placental cell growth, migration, and matrix production during pregnancy.

Immunolocalization of some HOX proteins in immature and mature feline testes.

Homeobox (HOX) proteins are known for their critical role in body shape formation and tissue differentiation of developing vertebrate embryos. Recent research has shown that HOX proteins have many physiological roles such as cell proliferation, cell cycle, apoptosis and cell differentiation in adults, as well as the development of the vertebrate nerve and reproductive system. This study was conducted to determine the possible physiological functions and expression intensities of HOXA10, HOXA11, HOXB6 and HOXC6 proteins in the male reproductive system (testes, epididymis and deferens ducts), which are important for the continuity of some specific cat breeds in different age ranges. In the study, a total of 18 testicular tissues were used, divided into two groups: less than 6 months (immature) and more than 1 year (mature). Tissue samples were then subjected to immunohistochemical staining with protein-specific antibodies examined in the study. In the findings obtained in the research; it was observed that HOXA10, HOXA11, HOXB6 and HOXC6 produced different intensities of immunolocalization in the epididymis and ductus deferens layers in the immature and mature testicular cells. In addition, it was found that HOXA10 immunoreaction was also seen in some vascular endothelial cells. As a result, it was concluded that the HOX proteins could contribute to the physiological functions of testes, epididymis and ductus deferens and affect male fertility.

The expressions of some metabolic hormones (leptin, ghrelin and obestatin) in the tissues of sheep tongue.

In this study, we aimed to observe the localization and expression of peptide hormones-leptin, ghrelin and obestatin-in the sheep tongue by immunohistochemistry. For that purpose, tongues of ten adult sheep were used. Leptin expression of moderate intensity was observed in the basal and parabasal epithelial cells of the luminal epithelium, and leptin was strongly expressed in the taste buds of the circumvallate and fungiform papillae and in von Ebner's glands. Ghrelin was primarily expressed in some of the skeletal muscle cells and the smooth muscle cells of the middle layer of blood vessels. A strong expression was observed in the epithelial cells lining the base of the groove surrounding the circumvallate papillae. Obestatin expression was particularly strong in the epithelial cells of the salivary ducts. It was also stronger in the von Ebner's glands than in the seromucous glands. Leptin, ghrelin and obestatin were shown to be produced at varying levels in different cell types, including epithelial, stromal and skeletal muscle cells, as well as in ganglion neurons, neural plexuses and blood vessels in the sheep tongue. Cellular localization and expression of these peptide hormones have not been investigated in many species including sheep.

Papillary Architecture and Functional Characterization of Mucosubstances in the Sheep Tongue.

This research aimed to reveal the general morphology and topographic distribution of lingual papillae, epithelial characteristics, mucosal structure, and glands with their mucin content in the sheep tongue, with consideration of species-specific characteristics. The tongues of ten sheep were analyzed for this purpose. Filiform and fungiform papillae existed within the borders of the ventral surface of the lingual apex. The majority of the filiform papillae had multiple secondary projections. Fungiform papillae were also seen on the lingual torus among lenticular papillae, as well as 6 to 10 circumvallate papillae arranged on its caudal border. The species-specific details of the general anatomical structure of the tongue were determined and, in general, the papillary organization in the sheep was similar to goats, while the papillary organization also was similar to features with deer species, specifically the filiform papilla from the mechanical papillae and fungiform papilla from the gustatory papillae. Neutral and weak sulfated mucins and N-acetyl sialomucins were located in seromucous glands, salivary duct epithelium and von Ebner's glands. Carboxylated acid mucins and N-acetyl sialomucins were not present in seromucous and von Ebner's glands. In seromucous glands, MUC1, MUC5AC, and MUC6 localized only in epithelial cells of ducts, whereas MUC2 localized in both glandular and ductal epithelial cells. All MUCs were present in both von Ebner's glands and salivary ducts. We showed that this mucin composition, may serve as a physical barrier in the initial section of the digestive system. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc.

Tissue distribution of some immune cells in bovine reproductive tract during follicular and luteal phase.

More recent studies indicate that immune cells which secrete their secretory products or cytokines play an important role in reproductive system. In our study, immune cell populations (CD8+ T lymphocytes, CD68+ macrophages, plasma cells, siderophages, eosinophils) and expression of major histocompatibility complex (MHC) class I and class II were examined in female reproductive tract during follicular (n = 13) and luteal phase (n = 10). Plasma cells and eosinophil granulocytes are present in few numbers in luminal epithelium, but abundant in longitudinal muscle layer of uterus, whereas siderophages are the dominant cell type in stroma. Moreover, MHC-I and -II+ cells are expressed by individual cells in organ layers, while CD8+ T cells and CD68+ macrophages are dominant in epithelium and muscle layer, respectively. In conclusion, we did not found significant changes in immune cells according to follicular and luteal phases, but localization and numbers in each organ have changed according to both organ and layers. These results indicate that these factors may play a crucial role not only to generate an immune response but also to have a role in regulation of physiological functions in female reproductive organs.

Mucin profiles of the abomasum in bulls and rams: A comparative study.

Many pathogens require direct binding to mucosal cells to cause an infection. The mucosal epithelium of the digestive tract, which is covered by a mucin layer, fulfills several protective functions that are essential to maintaining the health of the digestive tract. Mucins are glycoproteins, which are found on membranes and in mucus gels and protect the underlying mucosal cells. Both membrane-associated mucins and secreted mucins are critical components of mucosal defense. The aim of this study was to determine the localization and expression of mucin profile of the abomasum via histochemistry and immunohistochemistry. The abomasums of 20 bulls and 20 rams were evaluated. Histochemical examination showed that neutral and acidic mucins were present in the mucosa and the glands of the pars cardiaca, fundus, and pars pylorica of the abomasums of both bulls and rams. However, the expression of acidic mucins was weak in the superficial glands and strong in the deep glands of the abomasum of rams. In both bulls and rams, MUC1, MUC5AC, and MUC6 were expressed in the glandular epithelial cells in all regions of the abomasum. Interestingly, while MUC2 was not expressed in the pars cardiaca and fundus, it was weakly expressed in the parietal cells of the pars pylorica in both species. In conclusion, the presence of neutral and acidic mucins and MUC1, MUC2, MUC5AC, and MUC6 proteins in luminal epithelial and glandular cells of abomasum in the bulls and rams support the hypothesis that mucins play a key role in the protection of the abomasal mucosa against infectious agents.

Functional characteristics of the growth factor receptor family and some ligands in the oropharyngeal cavity of the Chukar partridge (Alectoris chukar).

1. The aim of the present study is to describe, immunohistochemically, the expression and cell type localisation of growth factor receptors and some of their ligands in the oropharyngeal organs of the Chukar partridge. 2. The tissue samples from 10 healthy adult partridges were dissected under ether anaesthesia and then embedded in paraffin following routine histological procedures. The immunoreaction for receptors and ligands of the epidermal growth factor receptor (EGFR)/ligand system was localised in the cell membrane, nucleus and cytoplasm of the luminal and glandular epithelial cells, stromal and striated muscle cells, and vascular endothelial and smooth muscle cells. 3. Variations were observed in the avian oropharyngeal organs. The immunostaining for the erbB1/HER1 (human epidermal growth factor receptor 1) and the EGF (epidermal growth factor) and AREG (Amphiregulin) ligands in the luminal epithelial cells was higher than in the glandular epithelial, stromal and striated muscle cells. However, the immunostaining for erbB3/HER3 (human epidermal growth factor receptor 3) and erbB4/HER4 (human epidermal growth factor receptor 4) were similar in the luminal epithelium, stromal and striated muscle cells. 4. Growth factor receptors and some of their ligands were localised in different cell types in the oropharyngeal organs. We suggest that erbB/HERs (human epidermal growth factor receptors) and their ligands play an important role in proliferation, differentiation, growth, survival and migration of the cells.

Immunohistochemical localization of epidermal growth factor system in the lung of the Japanese quail (Coturnix coturnix japonica) during the post-hatching period.

The purpose of this study is to determine the possible changes in the localization of the four Epidermal Growth Factor Receptors and three ligands in quail lungs from the first day of hatching until the 125th after hatching using immunohistochemical methods. Immunohistochemical results demonstrated that four EGFRs and their ligands are chiefly located in the cytoplasm of cells. Additionally, ErbB4, AREG, and NRG1 are localized to the nucleus and nucleolus, but EGF is present in the nucleolus. ErbB2 was also found in the cell membrane. In the epithelium of secondary bronchi, the goblet cells only exhibited ErbB1 and ErbB2, whereas the basal and ciliated cells exhibited EGFRs and ligands immunoreactivity. The atrial granular cells displayed moderate levels of ErbB1-ErbB3 and EGF and strong levels of ErbB4, AREG, and NRG1 immunoreactivity. While the squamous atrial cells and squamous respiratory cells of air capillaries and endothelial cells of blood capillaries exhibited moderate to strong ErbB2, ErbB4, AREG, and NRG1 immunoreactivity, they had negative or weak ErbB1, ErbB3, and EGF immunoreactivity. The expression levels of ErbB2-ErbB4, EGF, AREG, and NRG1 were also detected in fibroblasts. Although ErbB2 was highly expressed in the bronchial and vascular smooth muscle cells, weak expression of ErbB1, ErbB3, AREG and EGF and moderate expression of ErbB4 and NRG1 were observed. Macrophages were only negative for ErbB1. In conclusion, these data indicate that the EGFR-system is functionally active at hatching, which supports the hypothesis that the members of EGFR-system play several cell-specific roles in quail lung growth after hatching.

The profile of the epidermal growth factor system in rat endometrium during postpartum involution period.

The epidermal growth factor (EGF) plays a crucial role in the control of uterine cell proliferation, growth and differentiation. This study was designed to investigate the spatiotemporal expression pattern and localization of the EGF receptor/ligand system during the process of uterine involution using immunohistochemistry. Our results indicated that the expression of the ErbB/HER receptors and their ligands varied with structural changes in the uterus at different days of involution. Supranuclear punctate ErbB1 immunostaining was observed in the luminal and glandular epithelial cells and endometrial fibroblasts. Moderate ErbB2/HER2 immunoreactivity was observed in the lateral membrane and cytoplasm of the epithelial cells on the 1st, 3rd and 5th days and was decreased on the other days of involution. The amount of nuclear and cytoplasmic ErbB3/HER3 and ErbB4/HER4 immunostaining remained constant throughout the postpartum period. The EGF immunoreaction was weak in the luminal and glandular epithelium throughout the involution period. Although the cytoplasmic AREG immunoreactivity in the glandular epithelium was stronger on the 1st and 3rd days compared with the other days of involution, NRG1 immunostaining was weak on the 1st and 3rd days and was moderate in the apical cytoplasm on the 10th and 15th days of involution. The macrophages displayed strong cytoplasmic immunoreactivity for ErbB3/HER3, ErbB4/HER4, EGF, AREG and NRG. Strong, moderate and weak immunostaining for ErbB2/HER2, ErbB4/HER4 and other proteins (ErbB1, ErbB3, AREG and NRG), respectively, was present in the myometrial smooth muscle cells. These findings support the hypothesis that the EGFsystem plays a role in the development of various physiological changes associated with uterine involution.

Functional anatomy of the syrinx of the chukar partridge (Galliformes: Alectoris chukar) as a model for phonation research.

The phonation process of vertebrates is influenced by the material characteristics of the participating structures, ranging from molecular to macroscopic dimensions. Good animal models for phonation research are still lacking. Due to easy availability and relatively simple structure, the syrinx of birds might serve as a good animal model for this purpose. Our aim was therefore to determine structural features of the syrinx and obtain insights into its mucus layer characteristics. Epithelium and glands were analyzed using histological, histochemical, and immunohistochemical methods and conclusions were drawn on the use of the syrinx as a model for phonation research by comparing the epithelium and its mucus characteristics to human laryngeal secretions. Ten adult partridges were analyzed. The tympanum of the syrinx developed from the last two tracheal cartilages, whereas the caudal part of the syrinx was formed from eight pieces of bronchial cartilages. The tracheal and bronchial epithelia and the pessulus of the syrinx were lined by pseudo-stratified columnar epithelium in which goblet cells and intraepithelial glands were localized. Collagen fibers were distributed in the lamina propria of all parts of the syringeal mucosa. Elastic fibers in the membranes of the syrinx showed evident distribution. All glandular epithelial cells and goblet cells were positive for neutral, acidic and carboxylated mucins were dominant in particular. Epithelium and glands revealed positive reactivity with antibodies to the mucins MUC1, MUC2, and MUC5AC. Of these, MUC2 and MUC5AC were dominant. The syrinx of partridge can serve as a good ex vivo model for phonation research.

The expression of epidermal growth factor receptors and their ligands (epidermal growth factor, neuregulin, amphiregulin) in the bitch uterus during the estrus cycle.

In order to study the possible role of EGFR receptors in the bitch reproductive process, we have analyzed the expression pattern and localization of EGFR receptors and some of their ligands epidermal growth factor (EGF), neuregulin (NRG), amphiregulin (AREG), in the uterus during the estrus cycle using immunohistochemistry. The immunostaining for receptors and ligands of EGFR/ligand system was confined to membrane and cytoplasm of the target cells. Variations were observed, not only at the different stages of the estrous cycle, but also in the different tissue compartments of the uterus. However, it was detected that the immunostainings for NRG and AREG in the different cells do not show important differences at stages of the estrus cycle. In the luminal epithelium, strong immunostaining for ErbB1/HER1, ErbB2/HER2, ErbB4/HER4 and EGF was found at estrus. In the glandular epithelium, strong immunostaining for ErbB4/HER4 was observed at diestrus, while strong immunostaining for EGF was detected in both of estrus and diestrus. ErbB3/HER3 immunoreactivity in the stromal cells was higher at diestrus and anestrus, while ErbB4/HER4 immunoreactivity was lower at anestrus. In the myometrium, the highest levels of immunoreactivity of ErbB2/HER2 were found at estrus, while ErbB3/HER3 immunoreactivity was higher at anestrus. EGF immunoreactivity was lower at anestrus compared to other stage of cycle. Altered EGFR/ligand system expression during the estrus cycle suggests this growth factor system is a potent regulator of proliferation and differentiation events during preparation for implantation of bitch uterus.

Immunolocalization of vascular endothelial growth factor, its receptors (flt1/fms, flk1/KDR, flt4) and vascular endothelial growth inhibitor in the bitch uterus during the sexual cycle.

Angiogenesis is regulated by proangiogenic and antiangiogenic factors. Vascular endothelial growth factor (VEGF) is a prime proangiogenic regulator, whereas vascular endothelial growth inhibitor (VEGI) is a specific antiangiogenic cytokine. To clarify temporal changes in the localization of pro-angiogenic and anti-angiogenic factors in the uterus of normal bitches during the proestrus, estrus, diestrus and anestrus phases of the estrous cycle, the expressions of VEGF and its receptors (flt1/fms, flk1/KDR and flt4) and their correlation with VEGI were analyzed using immunohistochemistry. Uteruses were collected after ovariohysterectomy. Immunohistochemical staining was evaluated semi-quantitatively by an immunohistochemical total score consisting of the sum of the intensity and proportional scores. The results in the bitch uterus demonstrated that positive immunohistochemical staining was found exclusively in the cytoplasm and apical membrane of luminal and glandular epithelial, stromal and smooth muscle cells and nuclear staining was observed in the flt1/fms, flk4 and VEGI during proestrous and estrous. Semi-quantitative analyses revealed that the total score for VEGF in the glandular epithelial cells was significantly higher than that of luminal, endometrial stromal and myometrial smooth muscle cells during proestrous (p<0.05). The total score for flk1/KDR and flt4 in the glandular epithelium was also significantly higher than that of endometrial stromal cells during proestrous, whilst the total score for flt1/fms in the glandular epithelium was significantly higher than that of endometrial stromal cells during anestrus (p<0.05). We conclude that, in the bitch uterus, cyclic changes may be precisely regulated by the combined functions of VEGF family members, angiogenic VEGF and VEGF receptors, and the angiogenesis inhibitor VEGI.

The role of estrogen receptors, erbB receptors, vascular endothelial growth factor and its receptors, and vascular endothelial growth inhibitor in the development of the rat mammary gland.

We identified the localization and distribution of cell-specific epidermal growth factor receptors (EGFRs: erbB-1, erbB-2, erbB-3, erbB-4), vascular endothelial growth factor (VEGF), VEGF receptors [VEGFRs: VEGF-R1 (flt-1), VEGF-R2 (flk-1/KDR), VEGF-R3 (flt-4)], vascular endothelial growth inhibitor (VEGI), and estrogen receptor (ER), and determined whether or not these growth factors in rat mammary glands are functional. Thirty-five adult female Spraque-Dawley rats were randomly divided into five groups, each of which were at the 7th, 14th, and 21st day of pregnancy; 7th day post-delivery; and 7th day after weaning. It was determined that erbB, VEGF and its receptors, VEGI, and ER stained at different intensities. Intense staining was observed, in particular, in erbB receptors during pregnancy and involution, and also in VEGF and its receptors during lactation, while ER stained during the last periods of pregnancy and lactation. In conclusion, the expression of erbB, VEGF and its receptors, and ER were determined at varying intensities at different sites of the mammary gland during pregnancy, lactation, and involution periods.