Prenatal histomorphological development of the reticulum in fallow deer (Dama dama).

The histomorphological changes occurring in the Dama dama reticulum during prenatal development have been investigated. Twenty-five Dama dama embryos were used, from the first stages of prenatal life until birth. Differentiation of the reticulum was observed at 23% gestation. By 25% gestation the reticular wall comprised three layers: an internal epithelial layer, a middle layer of pluripotential blastemic tissue and an external layer or serosa. Primary reticular crests were visible at 38% gestation. Secondary reticular crests were observed at 61% gestation. Neuroendocrine cells were detected by synaptophysin (SYP) at 35% gestation, in the lamina propria-submucosa, tunica muscularis, and serosa. Epithelial Cytokeratin-18 (CK-18) cells were observed at 35% gestation extended throughout the epithelial layers. The glial cells (vimentin -VIM- and glial fibrillary acidic protein-GFAP-markers) were discerned at 25% and 43% gestation, respectively, in myenteric and submucosal plexuses, lamina propria, muscularis mucosae, tunica muscularis, and perivascular connective tissue. The neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) markers were immunodetected at 75% and 80 gestation, respectively, in the lamina propria-submucosa, muscularis mucosae, tunica muscularis, serosa, and myenteric plexuses. The prenatal development of the fallow deer reticular mucosa evidenced a considerable precocity similar to that previously reported in goat and red deer.

The embryonic development of the bovine stomach revisited.

The adult anatomy and physiology of the bovine (Bos taurus) stomach have been investigated extensively. Despite the many studies, however, the early development of the stomach has not yet been fully elucidated. The goal of the present study, therefore, was to review the available literature, to visualize the embryonic and early foetal development of the bovine stomach and to shed light on unresolved issues. The stomachs of fifteen bovine embryos and eleven foetuses from 26 to 80 days of gestation were photographed both in situ and after exenteration and critical point drying. A series of photographs was obtained that yielded a contiguous and comprehensive view of all the developmental changes that occurred until the virtually final configuration of the stomach was attained. In addition, the serosal surface was studied by electron microscopy, thus revealing subtle regional differences in the lining of the peritoneal cavity. Our observations corroborate the contention that all the compartments evolve from the fusiform primordium and that no outgrowth at the level of the oesophagus occurs. The greater curvature as well as the attachment line of the dorsal mesogastrium shift to the left, which is similar to the process in monogastrians. The rumen and reticulum develop from separate protrusions, and further compartmentalization results from constrictions and bulges and not from folding. Between 55 and 60 days of gestation, the entire bovine stomach except for the abomasum eventually relocates to its final position. In summary, previously debated key issues were addressed and integrated with current findings.

Histomorphometric and immunohistochemical study of the goat reticulum during prenatal development.

This study sought to describe the morphological changes taking place in the goat reticulum during prenatal development, using histomorphometric and immunohistochemical techniques. A total of 140 goat embryos and foetuses were used, from the first stages of prenatal life until birth. Differentiation of the reticulum as a separate compartment of the primitive gastric tube was observed at 35 days of prenatal life (23% gestation). By 38 days (25% gestation) the reticular wall comprised three layers: an internal epithelial layer, a middle layer of pluripotential blastemic tissue and an external layer or serosa. Primary reticular crests were visible at 59 days (38% gestation) as evaginations of the epithelial stratum basale, marking the earliest histological differentiation of future reticular cells. Secondary reticular crests were observed at 87 days (61% gestation). Corneum papillae first became apparent on the lateral surface of primary reticular crests at 101 days (64% gestation). The muscularis mucosae was visible by 101 days (64% gestation) in primary reticular crests. Neuroendocrine cells were detected by synaptophysin at 64 days (43% gestation), while glial cell markers (glial fibrillary acidic protein and vimentin) were observed at 64 days (43% gestation) and 38 days (25% gestation), respectively. The peptidergic innervation markers such as neuropeptide Y and vasoactive intestinal polypeptide were detected at 75 days (50% gestation). In conclusion, prenatal development of the reticulum - like that of the rumen - appears to take place somewhat earlier in goats than in sheep or cattle, but at a similar rate to that reported in deer.

Ontogenesis of the reticulum with special reference to neuroendocrine and glial cells: a comparative analysis of the Merino sheep and Iberian red deer.

The present study was designed to compare the differences in the ontogenesis of the reticulum in sheep (domestic ruminant) and deer (wild ruminant). A total of 50 embryos and foetuses Merino sheep and 50 Iberian deer were used, from the first pre-natal life until birth. The appearance of the reticulum from the primitive gastric tube was earlier in the sheep (22% gestation, 33 days) than in the deer (25% gestation, 66 days). In both cases, it displayed a primitive epithelium of a stratified, cylindrical, non-ciliary type. At around 48% gestation in the sheep (72 days) and 36% (97 days) in the deer, the reticulum was configured of four clearly differentiated layers: mucosa (with epithelial layer and lamina propria), submucosa, tunica muscularis and serosa. The stratification of the epithelial layer was accompanied by modifications in its structure with the appearance of the primitive reticular ribs. The primary ribs began to be formed first in the deer, at 117 days of pre-natal life (40% gestation) and later in the sheep (79 days, 53% gestation). The differentiation of the corneum papillae in the primary ribs coincided with the appearance of secondary reticular ribs. These structures began to be formed first in the deer, at 142 days of pre-natal life (51% gestation) and later in the sheep (83 days, 55% gestation). The presence of neuroendocrine cells (non-neuronal enolase-positive cells) in the reticular mucosa was not detected until 97 days (36% gestation) in deer and 81 days (54% gestation) in sheep. The presence of glial cells (GFAP-positive cells) occurred at around 142 days (51% gestation) in deer and at 112 days (75% gestation) in sheep. In conclusion, the presence of neuroendocrine and glial cells was detected in deer at earlier stages than sheep.

Morphometric and immunohistochemical study of the reticulum of red deer during prenatal development.

Iberian red deer need to be conserved for their economic role and for their genetic importance as an important component of the ecosystem. Modifications currently being made to traditional management systems require a better understanding of the structure, function and development of their alimentary system. Here we describe a histomorphometric and immunohistochemical analysis of the stomach of 25 red deer embryos and fetuses from 30 days of gestation until birth (235 days). Differentiation of the reticular compartment from the primitive gastric tube begins at 67 days, forming a three-layered structure: epithelium, pluripotential blastemal tissue and serosa. The primitive reticular cells are initiated as small epithelial evaginations (primary ribs) at 117 days. At 142 days, lateral growths appear from the primary reticular ribs, forming the corneum papillae. The secondary reticular ribs form at 142 days as growths from the primary ribs. The uneven height of primary and secondary reticular ribs leads to the formation of cells of varying size. Growth of the reticular ribs involves the lamina propria but not the submucosa, so clear separation of these layers is maintained during histodifferentiation. Formation of the tunica muscularis from the pluripotential blastemal tissue begins at 67 days of intrauterine life, as two layers of longitudinally and circularly arranged myoblasts. Differentiation of the muscularis from the mucosa occurs at approximately 205 days, as longitudinal projections of the internal bundles of the tunica muscularis form the musculature of the primary ribs. The secretion of neutral and acid mucopolysaccharides by the reticular epithelial layer begins at 67 days, establishing the gradual adaptation of the mucosa to its protective function in postnatal life. Neuroendocrine (non-neuron enolase) and glial cells (glial fibrillary acidic protein and vimentin) were detected by immunohistochemistry, in a similar localization and intensity to that reported in the rumen. The neuropeptides vasoactive intestinal peptide and neuropeptide Y showed a positive immunoreaction in the reticular epithelium from 142 days of prenatal life, again earlier than reported for the rumen. In comparison with domestic ruminants, deer were shown to be less precocious with regard to development of gastric tube, in their capacity to secrete neutral mucopolysaccharides, and in their neuroendocrine nature, as determined by the detection of positive neuroendocrine and/or glial cells.

Three-dimensional development of bovine reticular cell (Cellula reticuli).

This paper describes the three-dimensional construction of the reticular cell, cellula reticuli, in bovine reticulum and its ontogenetic development. Reticular cells of fetal suckling calf and adult tissues were investigated both at the surface of intact mucosa and macerated samples using scanning electron microscopy. At the third month of gestation, the formation of the reticular cells on the mucosal surface started from the center of the cell and just above the reticular crest. The reticular crests were observed on the surface of the macerated sample at an earlier period of gestation (third month). In the eighth month of gestation, primary, secondary and tertiary reticular crests and papillae could be observed from the mucosal surface. Macerated samples showed that those structures were already formed completely under the epithelium by the first half of the seventh month of gestation. It is suggested that the development of the reticular papillae starts from the lower to the upper parts of the reticular cell.

[Comparative ontogenic analysis of the epithelium of the non-glandular stomach compartments of merino sheep]. / Estudio ontogenico comparativo de la lamina epitelial de los compartimentos gastricos no glandulares en ovinos merinos.

A total of 74 embryos and fetuses were used in a comparative analysis of the epithelium of the non-glandular stomach compartments of merino sheep during development. The mechanical protection showed by the tegumentary epithelium in the superficial layers of the rumen, reticulum and omasum is supported by a buffer system of neutral mucopolysaccharides secreted by the deeper strata. Neutral mucopolysaccharides first appeared in epithelial cells at 46 days of fetal life. Acid mucopolysaccharides, mucins, and mucoid compounds were not detected. Growth curves and formulas were constructed for the epithelial layers.

Histomorphometric analysis of the reticulum of the sheep during development.

Histomorphometric and scanning electron microscopic analysis were performed on 74 embryos and foetuses and on 20 sheep (early post-natal to adult age). Histodifferentiation of the reticulum took place at 33 days of foetal life. Reticular ribs were observed as evaginations of the epithelial stratum germinativum at 64 days. Neutral mucopolysaccharides first appeared in epithelial cells at 46 foetal days, thereafter to decrease gradually in number, subsequently stabilising in postnatal life. Acid mucopolysaccharides, mucins and mucoid compounds were not detected. Growth curves and formulae were constructed for each tissue layer. Initial test involved multiplicative (y = axb), linear (y = a+bx) and polynomial model (y = a+b+cx2+dx3).

[The development of the bovine stomach: morphologic and morphometric analysis. III. Spatial and morphometric reconstruction]. / El desarrollo del estómago del vacuno: análisis desde el prisma morfológico y morfométrico. Parte III: Reconstrucción espacial y morfometría.

This work represents a summary of the study presented in parts I and II, previously published in this journal. The data collected in those studies is presented in three dimensional reconstructions of the stomach of the developing calf.

Histogenetic evolution of bovine gastric compartments during the prenatal period.

In order to carry out this study, 62 embryos and fetuses of Friesian cows were used, and every stomach was dissected and subjected to the usual laboratory procedures. After obtaining each preparation all the histological and metrical changes that took place in the wall of the viscus during its development are described. The compartments are histologically differentiated into three stages: in the first one there is no compartment differentiation: in the second one, the rumino-reticulum, omasum and abomasum have differentiated; and in the third one every compartment is differentiated. In group 16, (78 days of gestation), a decrease in thickness of the muscular layer of all compartments, parallel to the histological differentiation has been observed.

[The development of the bovine stomach: morphological and morphometrical analysis. I. Morphogenic observations of the ruminoreticulum]. / El desarrollo del estómago del vacuno: análisis desde el prisma morfológico y morfométrico. Parte I: Observaciones morfogénicas asociadas al bloque ruminorreticular.

Forty-two embryos and fetuses of Frisian cattle, distributed onto 14 groups on the basis of crown-rump lengths between 1.3 cm (about 23 days) and 9.5 cm (70 days), were to study the morphogenesis of the bovine stomach. The work is divided into three parts. Part 1 deals with the ruminoreticulum and parts II and III the omasum and abomasum.

Histological development and histochemical localization of enzymes in rumen and reticulum in bovine fetuses.

Thirty Holstein fetuses from 100 to 251 d after conception were utilized to study prenatal anatomical development of the epithelium of the rumen and reticulum. Four calves at birth were included in the study for comparison. Tissue sections were frozen and stained to locate specific enzymes. At 100 d, the epithelial layer of the rumen was differentiated into a thin basal zone and a thickened superficial zone of undifferentiated cells. The basement membrane was straight, and in both zones cells were perpendicular to it. At 120 to 141 d, low, primary undulations were detected in the basal zone, basement membrane and underlying lamina propria. At 150 to 166 d, secondary undulations and incipient papillae began to resemble the papillae of mature mucosa. In rumen papillae of 192-d to 215-d fetuses, shallow furrows began to separate papillae apexes from the mass of epithelium. In fetuses 244 to 251 d, the papillae began to be a separate entity. At birth, the basal position of the papillae still remained fused. An incipient separation between the papillae was seen. Several dehydrogenase enzymes, including those associated with the Krebs cycle and reductase associated with energy transformation, were observed in both ruminal and reticular tissue. Alkaline phosphatase activity was localized in the stratum corneum and in blood vessels. Development of the honeycomb configuration of reticular epithelium was evident in the 100-d fetus and progressed rapidly with age.

Studies on the histogenesis of the tunica mucosa of the stomach of the Egyptian water buffalo (Bos bubalus L.). II. Histogenesis of the reticular mucosa.

In the fetus with 9 cm CRL the reticular mucosa was made up of a Lamina epithelialis and a Lamina Propria/submucosa. The primordia of the reticular crests firstly appeared in the fetus with 16 cm CRL as evaginations of the basal zone of the Lamina epithelialis into the superficial one. Invaginations from the luminal surface of the Lamina epithelialis above the tips of the long reticular crests were formed in the fetus with 27 cm CRL. Aggregations of smooth muscle cells appeared in the cores of the long reticular crests in the fetus with 50 cm CRL. In the fetus with 73 cm CRL invaginations of various depths were formed to separate the reticular crests from the mass of epithelium. The epithelium in the different fetal stages were missing a Stratum corneum.

Histological and histochemical observations on the forestomach of goat during pre-natal life.

Non-keratinized, stratified squamous epithelium lined the mucosa of the fore-stomach. The mucosal appendages in the form of ruminal papillae did not develop in the rumen during this study, however, omasal laminae and reticular ribs were evident in groups I and II, respectively. Cytoplasmic accumulations were evident in the middle layer of the epithelium, which is characteristic of this region. The thickness of the epithelium increased constantly in the rumen and reticulum, but in the omasum it remained constant with the increase in the size of the fetus. The corial papillae in the rumen, reticulum and omasum appeared at the 12.7-, 11.5-and 14.6-cm CVR stage, respectively. The muscularis mucosae appeared in the omasum at the 14.6-cm CVR stage in the first-order laminae. The tunica muscularis consisted of spirally arranged muscle fibre bundles. Cross-cut muscle fibre bundles below the tip of the omasal laminae descended downward with the increase in the size of the fetus and continued with the inner circular layer. Acid and alkaline phosphatases and fat could not be observed. The concentration of glycogen in the epithelium was maximum in group III and minimum in group II.