In spite of numerous, substantial advances in equine reproduction, many stages of embryonic and fetal morphological development are poorly understood, with no apparent single source of comprehensive information. Hence, the objective of the present study was to provide a complete macroscopic and microscopic description of the equine embryo/fetus at various gestational ages. Thirty-four embryos/fetuses were aged based on their crown rump length (CRL), and submitted to macroscopic description, biometry, light and scanning microscopy, as well as the alizarin technique. All observed developmental changes were chronologically ordered and described. As examples of the main observed features, an accentuated cervical curvature was observed upon macroscopic examination in all specimens. In the nervous system, the encephalic fourth ventricle and the encephalic vesicles forebrain, midbrain, and hindbrain, were visualized from Day 19 (ovulation = Day 0). The thoracic and pelvic limbs were also visualized; their extremities gave rise to the hoof during development from Day 27. Development of other structures such as pigmented optical vesicle, liver, tail, cardiac area, lungs, and dermal vascularization started on Days 25, 25, 19, 19, 34, and 35, respectively. Light and scanning microscopy facilitated detailed examinations of several organs, e.g., heart, kidneys, lungs, and intestine, whereas the alizarin technique enabled visualization of ossification. Observations in this study contributed to the knowledge regarding equine embryogenesis, and included much detailed data from many specimens collected over a long developmental interval.

RESUMO.-O tipo de alimentação depende do ambiente em que o animal se encontra, sendo este um fator responsável pela alteração da morfologia, como a estratiϐicação e o nível de queratinização da língua, e a funcionalidade da mesma. Dentre as estruturas morfológicas funcionais da língua, as papilas vêm merecendo destaque devido a sua estreita relação com a dieta. Foram utilizadas duas espécies de cervídeos: cinco Mazama gouazoubira e duas Mazama americana, dividindo-se a língua em três partes: ápice, corpo e raiz. Analisou comparativamente a língua de duas espécies por meio de microscopia de The type of feeding is dependent on the environment in which the animal lives, fact that's responsible for changes in morphology such as stratiϐication, level of keratinization and functionality. Among the functional morphological structures of the tongue the papillae are worth mentioning due to their close relation to the diet. Two Cervidae species were used, ϐive Mazama gouazoubira and two Mazama americana. Their tongues were divided into three parts, apex, body and root, and comparatively analyzed by light and scanning electron microscopy. The ϐiliform, fungiform and vallate papillae were present in the two species' tongue and presented the same distribution, differing only in the quantity of vallate papillae on the root of the tongue, fact that might be related to the diet. Moreover, their distribution resembles that of other herbivore species.

Since the horse has a highly precocial reproductive strategy, most organs are functionally well developed at birth and thus, embryonic and fetal life is interesting. Data on the development of important organs are very limited. Here, we detailed macroscopically and histologically the equine digestive system, focusing on the first third of gestation. At 21 days, the oral cavity was an empty space, and the liver contained proliferating endodermal cells. At 25 days, a fusiform stomach and the pancreatic bud were present. At 28 days, a small tongue and the esophagus occurred. At 30 days, primary and secondary palates were developed, the liver contained cords of hepatocytes, and the pancreas was triangular. At 40 days, crypts had formed in the intestinal loops, cell differentiation was observed in the hepatic parenchyma, and the pancreas was elongated. Pancreatic acini and islets were observed in fetuses of 50 days and intestines were highly convoluted. Three segments of the pharynx were distinguishable at 75 days. At 105 days, the intestinal villi were wide with round tips; especially, the liver, stomach, and oral cavity showed key steps of anatomical and cellular differentiation in early fetuses, whereas other areas, such as pancreas or pharynx were still immature in the investigated phase. Pluripotency analysis using Oct4 showed initial intense staining in all of the digestive system tissues and a later decreased becoming restricted to specific cell layers. In conclusion, our data may contribute to perform a chronological reference of developmental events for approaches predicting pregnancy disorders in horses.

Pesq. Vet. Bras. 31(Supl. The morphology of the lingual papillae of domestic goat (Capra hircus) was studied by scanning electron microscopy (SEM) and light microscopy (LM). Filiform, conical and lentiform papillae exert mechanical function whereas fungiform and valate papillae have gustative function. Filliform papillae were distributed all over the lateral and dorsal surfaces of the tongue. They present a conical shape with the thin ends pointed caudally; and possess several secondary processes, of different sizes, with the same orientation. Histological examination of these papillae revealed abundant queratinized tissue. Fungiform papillae were observed on the dorsal and lateral surface of the apical region and body of the tongue. Present a fungi-like shape, with a thick corniϐied epithelium and taste buds distributed on the surface. Lentiform papillae were distributed over the median line of the dorsal torus, presenting projections above the surface of the tongue. Some displayed pyramidal shapes; other were more ϐlattened. Valate papillae were observed on the lateral surface of the posterior part of the torus and present a rounding shape delimited by a deep groove. These papillae possess taste buds on their lateral wall that open up on the groove. Conical papillae were observed on the lingual torus and present an extended shape, with a wide base and a blunt tip. Although the main morphological and structural characteristics of the lingual epithelium are species-speciϐic, some features may be inϐluenced by the type of food and alimentary habits. Therefore, the present study provides a histological and ultrastructural description of the tongue of the domestic goat fed with mixed food (grass and concentrate).INDEX TERMS: Tongue, lingual papillae, scanning electron microscopy.