Computed tomography study of the fetal development of the dairy cow stomach complex.

In the fetal development of animals, critical physiological and anatomical events influence the long-term health and performance of the offspring. To identify the critical growth phases of the fetal bovine stomach, we used computed tomography imaging on 30 German Holstein fetuses to examine the fetal bovine stomach in situ. Computed tomography allows the study of diverse parameters such as the volume of the stomach chambers in situ without the need for sophisticated filling preparation techniques. The absolute volume, relative volume, and monthly volume increase of each stomach chamber were determined. Computed tomography was a reliable method for in situ examination of the fetal bovine stomach complex from the third month of gestation onward. It was able to detect an abnormal position of the abomasum in 2 fetuses. The crown-rump length of the fetuses studied ranged from 9.5 to 89 cm (from 2.2 to 8.3 mo of gestation). Over this timeline, the changes in the relative volumes of the ruminoreticulum and abomasum were inversely related. Until mo 5 of gestation, the relative volume of the ruminoreticulum increased steadily, whereas that of the abomasum decreased. Thereafter, the relative volume of the ruminoreticulum became gradually smaller, and that of the abomasum became larger; by mo 8, the abomasum was larger than the ruminoreticulum. All stomach chambers had large increases in volume over the gestation period and we observed differences in development patterns and volume changes of the individual stomach chambers over this period. The largest monthly volume increase of the stomach complex was between mo 4 and 5 of gestation. In this period, the volume of the ruminoreticulum increased 43.8 times, that of the omasum 38.9 times, and that of the abomasum 30.03 times. Between mo 5 and 6 of gestation, the abomasum had another growth spurt, with a monthly volume increase of 10.4 times. These 2 time points in the gestation period may be critical phases of fetal development that should be considered in the management of pregnant cattle.

Histomorphometric study of the goat stomach during prenatal development.

The aim of this study was to perform a morphometric analysis of the different structural tissue layers of the goat stomach to study their prenatal growth from mathematical models fitted to these morphometric data. A total of 90 embryos and fetuses were used, from the early stages of prenatal life until birth. The growth rate of the gastric wall was slower than that of body length; rumen was the stomach compartment displaying slowest growth. In the three non-glandular compartments, the epithelial layer grew faster than the gastric wall itself, while the growth rate of the abomasal epithelium declined in the early stages of development. A decline in growth rate was also observed for the lamina propria and submucosa in rumen and reticulum from the early embryonic stages, whereas in omasum and abomasum these layers continued to grow as gestation progressed. The tunica muscularis displayed consistent growth in all compartments, growing faster than the gastric wall. Serosa thickness increased as gestation progressed, displaying a decline in growth-rate only in the omasum. In conclusion, the dynamics of gastric wall growth were governed by the growth rate of each of the component tissue layers.

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

This work studies the morphological changes taking place in the goat omasum during prenatal development, using scanning electron microscope, light microscopy and immunohistochemical analysis. A total of 140 goat embryos and fetuses were used, from the first stages of prenatal life until birth. Differentiation of the omasum as a separate compartment of the primitive gastric tube was observed at 35 days of prenatal life ([crown-rump length (CRL)] 3 cm, 23% gestation). By 38 days (CRL 4.3 cm, 25% gestation) the omasal wall comprised three layers: an internal epithelial layer, a middle layer of pluripotential blastemic tissue and an external layer or serosa. Omasal laminae appeared in the following order: primary at 38 days (CRL 4.3 cm, 25% gestation), secondary at 50 days (CRL 7.7 cm, 33% gestation), tertiary at 59 days (CRL 12 cm, 39% gestation) and quaternary at 64 days (CRL 13.5 cm, 43% gestation). Neuroendocrine cells were detected by synaptophysin (SYP) at 52 days (CRL 8 cm, 35% gestation), while glial cell markers (glial fibrillary acidic protein - GFAP, and vimentin-VIM) were observed at 64 days (CRL 13.5 cm, 43% gestation) and 38 days (CRL 4.3 cm, 25% gestation), respectively. Sympathetic and parasympathetic nerve fibers and nerve bodies were detected via neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) at 95 days (CRL 20 cm, 63% gestation). In conclusion, prenatal development of the omasum - like that of the rumen - appears to take place somewhat earlier in goats than in sheep or cattle, but at a similar stage to that reported in deer.

Ontogenesis of the omasum: a comparative analysis of the Merino sheep and Iberian red deer.

The aim of this study is to describe differences in the ontogenesis of the omasum in sheep (domestic ruminant) and deer (wild ruminant). A total of 50 embryos and fetuses of Merino sheep and 50 Iberian deer were used, from the first stages of prenatal life until birth. For the study, the animals were divided into five experimental groups according to the most relevant histological characteristics. The appearance of the omasum from the primitive gastric tube was earlier in sheep (22% gestation, 33 days) than in deer (25% gestation, 66 days). In both cases it displayed a primitive epithelium of a stratified, cylindrical, non-ciliary type. The appearance of four laminae of different sizes was always earlier in sheep than deer. At around 36% gestation in sheep (53 days) and 36% (97 days) in deer, the omasum consisted of 4 clearly-differentiated layers: mucosa (with epithelial layer and lamina propria), submucosa, tunica muscularis and serosa. The temporal order of appearance of the four order laminae and omasal papillae was always earlier in sheep than deer. The tegumentary mucosa of the omasum was without secretion capability in the first embryonic phases. From 67 days (26% gestation) the neutral mucopolysaccharides appeared in deer and at 46 days (30% gestation) in sheep. In both cases they continued to decrease until birth, this decrease being more pronounced in deer. Finally, the presence of neuroendocrine and glial cells was detected in deer at earlier stages than in sheep.

Studies on the development of omasum in West African dwarf goats (Capra hircus).

This work studied the sequential morphological changes of omasum in foetuses, neonates and adult West African Dwarf (WAD) goats by gross and light microscopic methods. The mean omasal volume was 1.37 +/- 0.36, 4.2 +/- 0.4, 8.7 +/- 6.9 and 60.1 +/- 8.6 ml for gestation day 87 and 146 foetuses, neonates and adults respectively. Grossly the mucosa exhibited longitudinally oriented primary, secondary, tertiary and quartnery laminae with smooth surface in foetuses and numerous papillae in the adults. Microscopically it was lined by stratified squamous epithelium which was divided into larger lighter luminal and smaller darker basal zones in gestation day 60 foetuses. The core of the laminae contained extension of the inner muscular tunic. The basal zone developed lateral evaginations (corial papillae) into the lighter zone of the laminae in gestation day 106 foetuses. By term these corial papillae approached the luminal surface. The papillae emerged above the luminal surface in 4 week old neonates. The papillae were fully developed in adult goats. The mean papillary height and width were -205.1 +/- 34.0, 67.0 +/- 9.6; 235.0 +/- 86.5, 185.0 +/- 42.3 and 570.3 +/- 60.0, 290.1 +/- 66.3 microm for foetuses, neonates and adult goats. The inner circular layer was thicker than the outer longitudinal layer of the muscular tunic. The central muscular layer of the laminae originated from the inner circular layer with attachment to the outer muscular layer in adults. This attachment could be adaptation for better anchorage and muscular contraction of the laminae in WAD goats.

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

The red deer is an important study species because of its value in the national economy and because it provides a wealth of genetic material. To date, there has been little research into the prenatal development of the stomach of ruminants, and none of the red deer. We therefore performed a histological evaluation of the ontogenesis of the omasum in the red deer. Histomorphometric and immunohistochemical analyses were carried out on 50 embryos and fetuses of deer from the initial stages of prenatal life until birth. For test purposes, the animals were divided into five experimental groups: Group I (1.4-3.6 cm crown-rump length, CRL; 30-60 days, 1-25% of gestation); Group II (4.5-7.2 cm CRL; 67-90 days, 25-35% of gestation); Group III (8-19 cm CRL; 97-135 days, 35-50% of gestation); Group IV (21-33 cm CRL; 142-191 days, 50-70% of gestation); and Group V (36-40 cm CRL; 205-235 days, 75-100% of gestation). At 67 embryonic days, the omasum wall was differentiated, and comprised three layers: the epithelial layer, pluripotential blastemic tissue and serosa. The stratification of the epithelial layer was accompanied by changes in its structure, with the appearance of four laminae of different sizes; in order of appearance these were: primary at 67 days, secondary at 90 days, tertiary at 97 days and quaternary at 135 days. At around mid-gestation, lateral evaginations were formed from the stratum basale of the primary and secondary smaller laminae. These were the primitive corneum papillae. From 205 days, the corneum papillae were present in all four sizes of laminae. The histodifferentiation of the lamina propia-submucosa, tunica muscularis and serosa showed patterns of development similar to those reported for the rumen and reticulum of red deer. The omasum of red deer during prenatal life, especially from 67 days of gestation, was shown to be an active structure with full secretory capacity. Its histological development, its secretory capacity (detected by the presence of neutral mucopolysaccharides) and its neuroendocrine nature (detected by the presence of positive non-neuronal enolase cells and the neuropeptides vasoactive intestinal peptide and neuropeptide Y) were parallel to the development of the rumen and the reticulum. However, its prenatal development was later than that of the omasum in sheep, goat and cow.

[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 omasum of sheep during development.

Histomorphometric and scanning electron microscopic analyses were performed on 74 embryos and fetuses and 20 sheep (early postnatal to adult age). Histologic differentiation of the omasum took place at 33 days of fetal life, with the appearance of first-order laminae. Second-, third-, and fourth-order laminae appeared at 39, 50, and 59 days, respectively. Neutral mucopolysaccharides first appeared in epithelial cells at 46 days of fetal life, decreasing quantitatively until birth, before subsequently stabilizing in postnatal life. Acid mucopolysaccharides, mucins, and mucoid compounds were not detected. Growth curves and formulas were constructed for each tissue layer. Initial tests involved multiplicative (y = axb), exponential (y = EXP [a + bx]), linear (y = a + bx), and polynomial models (y = a + bx + cx2 + dx3).

[The development of the bovine stomach: morphologic and morphometric analysis. II. Observations of the morphogenesis associated with the omasum and abomasum]. / El desarrollo del estómago del vacuno: análisis desde el prisma morfológico y morfométrico. Parte II: Observaciones morfogénicas asociadas al bloque omaso-abomásico.

This study represents a continuation of part 1 of a study of the development of the bovine stomach. Material and methods are more fully described in part i of the study. In this part 2 of the study further developmental stages and morphometric analysis is presented.

[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.

[Fetal development of the omasum of cattle (Bos taurus)]. / Zur fetalen Entwicklung des Blättermagens des Rindes (Bos taurus).

Structures characteristic of the omasum are already present by the third month of development. The fetal omasal laminae exhibit their typical arrangement (1434243414). Muscle fibers from the lamina circularis also extend into the first through third order laminae at this stage. Conical projections and small secondary papillae begin to appear on the laminae as the fetus ages. The lamina muscularis mucosae can be found in all of the laminae by the fourth to fifth month of development. The cuboidal to columnar epithelium of the stratum basale remains largely unaltered throughout the course of fetal development, whereas the stratum superficiale is subjected to a continuous series of changes. Superficial cell layers increase and the glycogen content of the epithelial cells fluctuates significantly.

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.

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.

Development of the omasum in sheep.

Data are presented on the histogenesis of the omasal mucosa in sheep from the 2.5 cm crown-rump (c-r) length fetus to the adult. 11 stages of fetal development, and 4 post-natal stages, were studies. The distribution of glycogen in the omasal epithelium was also studied. During fetal life the omasal epithelium was initially stratified cuboidal in type, but the superficial layers of cells became flattened in later stages of gestation. This epithelium became extremely thick by the late stages of fetal life, reaching a maximum of 358 micron, and consisting of greater than 20 layers of cells, in the 45 cm c-r fetus (approximatelay 140 days). After birth the epithelium became markedly reduced in thickness, being approximately 77 micron in the adult, and had differentiated into a cornified stratified squamous epithelium of the adult type by 12 weeks after birth. Glycogen was extremely abundant in the omasal epithelium of the 2.5 cm fetus, and declined gradually thereafter to be almost completely absent in post-natal specimens. 4 orders of laminae were present in the adult omasum, distributed in the seqeunce 1-4-3-4-2-4-3-4-1. The 1st order was already present in fetuses of 2.5 cm c-r length, with the 2nd, 3rd and 4th appearing by the 3.5, 5.5 and 11.0 cm stages, respectively. Initial stages in the development of conical papillae were first seen in 15.0 cm fetuses, but the development of these papillae was not completed until after birth.