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BACKGROUND: Developmental anatomy is a prerequisite for a real understanding of gross anatomy and teratology. It is concerned with the sequential stages of embryonic and fetal development, beginning with fertilization. Moreover, it helps to describe developmental changes and abnormalities, heredity, sexing, and the appearance of vestigial structures. Powerful advancements in molecular genetic manipulation and assisted reproductive technologies are employed during embryo and fetal development, and these efforts have had profound impact on animal production worldwide. OBJECTIVES: The present study was carried out to investigate the onset and stages of osteogenesis in rabbit (Oryctolagus cuniculus). METHODS: Forty mature rabbits (33 does and 7 bucks) with a mean weight of 2 kg were included in this study. They mated twice at a ratio of three does to one buck on day zero (0). Mounting was carefully observed to ensure mating occurred and was confirmed by the physical examination of the vulva for swelling and redness, while pregnancy diagnosis was confirmed by ultrasonography and abdominal palpation. Embryos and fetuses were extracted via a ventral incision on the abdominal and uterine walls of one pregnant doe each day after euthanization with thiopental sodium at the dose of 31 mg/kg body weight intravenously. Diaphonisation was employed in studying osteogenesis. RESULTS: Osteogenesis began at fetal day 21 (F21) using diaphonisation. In the skull, the bones of the splanchnocranium appeared before the neurocranium. The centrum and transverse processes were the first identifiable features of all different types of bone in the vertebral column to be ossified. The spinous process and the fusion of the sacrum and sternum were not detected throughout the gestation period. It was also observed that the epiphyseal and articular ends of none of the bones, neither in the fore nor hind limbs were ossified throughout gestation. Specifically, while the primary ossification centers of the middle phalanges were the last to appear in the manus and pes, all the carpals were absent, and only the calcaneous was evident in the tarsal bones. CONCLUSIONS: We recorded the onset of osteogenesis and subsequent development throughout the gestation period of rabbits, which has added some valuable information to the documented literature on the bone development of this species. [ABSTRACT FROM AUTHOR]

The investigation of gross anatomical features of the gastro - intestinal tract (GIT) of the guinea pig (Cavia porcellus, Linnaeu-1758) was carried out. The aim of the study was to describe the gross anatomical anatomical features of the gastro - intestinal tract (GIT) of the guinea pig (Cavia porcellus, Linnaeus-1758). Fifteen healthy adult guinea pigs of both sexes were purchased from Samaru market in Zaria. The animals were anaesthetized and sacrificed, with the oesophagus, tongue, stomach, small and large intestines, liver, and gall bladder dissected. The tissue samples were immediately fixed by complete immersion in 10 % normal formalin, labeled and fixed. The various segments of the GIT were weighed, measured and photographs were taken. The results of the morphologic studies showed that the oesophagus was a direct continuation of the pharynx, extending from the pharynx to the cardia of the stomach. The oesophagus lay dorsal to the trachea throughout its length until it entered the stomach. The stomach showed three regions, namely; cardia, fundus and pylorus, while the small intestine showed also three regions, namely; the duodenum, the jejunum and the ileum. The large intestine had three distinct regions; the caecum, the colon and the rectum. The liver was divided into four lobes, namely: the right, the left, the intermediate and the accessory lobes. The gall bladder was observed as a sac-like structure, with a light yellowish green colouration. The tongue was observed as a mass of striated muscle fibers covered by a mucous membrane. This work concluded that the gastrointestinal tract of guinea pig was similar to those of other rodents. [ABSTRACT FROM AUTHOR]

The relationships between the body dimensions, age and weight in the eighty-seven foetuses were determined. Each foetus was weighed and its body dimensions were measured using a string and a measuring tape. The sexes of the foetuses were determined by observing and recording the gonad type in the ventral caudal area. The age of each foetus was determined by measuring the crownrump length. The mean (± SEM) weight of the foetuses ranged from 50.7 ± 7.4 g - 14350 ± 3372 g. The crown-rump length and body length of the foetuses varied from 15.8 ± 1.2 cm - 104 ± 8.5 cm and 20.5 ± 1.7 cm - 137 ± 11.7 cm, respectively. The tail length and neck length ranged from 3.3 ± 0.2 cm - 24.5 ± 2.4 cm and 5.7 ± 0.5 cm - 36.9 ± 2.6 cm, respectively. The relationships between the mean crown-rump length and body length of the foetuses were highly significant (P < 0.001). The mean crown-rump length of the foetuses were significant (P < 0.001) correlated with age, body weight, body length, tail length and neck length. Body length was significantly (P < 0.001) related to age, weight, tail length and neck length. The increase in tail length to neck length occurred at a fairly constant ratio of 1:8. [ABSTRACT FROM AUTHOR]

Summary: The hindlimb of the grasscutter (Thryonomys swinderianus, Temminck‐1827) was studied using 12 adult (≥6 months) rats of either sex with the mean weights of 1.42 ± 0.20 kg and 0.82 ± 0.13 kg for buck (n = 6) and doe (n = 6), respectively (p < .05). Characteristics of the bones were studied by gross observation after their preparation. Measurements of different segments of the hindlimb were also taken, giving a total average length of 31.80 cm. Correlation coefficients between length of bone and weight of rats were positive (p < .05) in bucks for all bone segments, except the pes (p > .05), whereas those in does were all non‐significant (p > .05), with significant sexual dimorphism in the relationships. The average total number of bones in the hindlimb was 92, with no apparent sexual dimorphism. The bones of the hindlimb revealed important differences and similarities in morphology with those of other rodents. The Os coxae presented a relatively large obturator foramen, formed by the ramus of the ischium and shaft of the pubis. The femur had a body and two extremities with a prominent head, well‐defined neck and trochanter. The fibula, a slender bone with triangular‐shaped proximal extremity, ran down the length of tibia with proximal attachment (via cartilage) and distal fusion, leaving an extensive interosseus space. The pes revealed eight tarsals and four metatarsals; each of the metatarsals showed three phalanges. [ABSTRACT FROM AUTHOR]

The study was conducted to evaluate the sexual dimorphism in the morphometric parameters of the whole brain and the brainstem in adult captive African giant pouched rats. Twenty-nine brain samples, comprising 15 females and 14 males, were utilized. Following brain extraction by standard procedures, the mean values of the weights, lengths, diameters, and volumes of the intact brains and the brainstem structures were compared in male and female rats using quantitative analytical statistical methods. The absolute brain weight obtained in the male was significantly higher (p < 0.01) than that of the female while the relative brain weight obtained in the female (0.636 +/- 0.049%) was higher than that of the male rats (0.564 +/- 0.032%), although the difference in the values was not statistically significant (p > 0.05). The lengths of the brain and myelencephalon, as well as the weights of the myelencephalon and mesencephalon, did not differ between the two sexes (p > 0.05). The weights and lengths of the pons did not differ between the two sexes (p > 0.05). There was a significant difference (p < 0.05) in the pyramidal length and a highly significant difference (p < 0.01) in the pyramidal width between the two sexes, with the male rats having higher values. This pioneering sexual dimorphic brain morphometry provides information for further research.

Bovine fetal lung tissue was examined histochemically, using alpha-naphthyl butyrate (nonspecific method), to detect the presence of esterase-positive pulmonary alveolar macrophages (PAM). Positively stained PAM were first seen in the alveolar septa and lumina of the lungs of 4 of 8 fetuses 240 days old. Macrophages (n = 100) in 240-day-old fetuses were 6.74 +/- 0.07 microm, and in most cells, esterase-positive granules were sparsely distributed in the cytoplasm. In 10 fetuses 250 days old, the alveolar septa and lumina of lungs contained positively stained macrophages, as did those of all older fetal lungs examined. Compared with macrophages of the 240-day-old fetuses, those (n = 50) of 250-day-old fetuses were significantly larger, 7.32 +/- 0.10 micron (P less than 0.0001), and esterase-positive granules were heavily distributed throughout the cytoplasm. In all fetal lungs, T lymphocytes contained a single, small, esterase-positive granule, compared with the numerous diffuse esterase-positive granules in PAM. Type-II pneumonocytes with well-developed lamellar bodies had no evidence of positive nonspecific esterase reaction in lungs.

The breathing patterns of 20 anesthetized chickens were studied during progressive suppression of intrapulmonary chemoreceptors (IPC) by various concentrations of CO2 and following bilateral vagotomy. The vagotomy breathing pattern, characterized by a marked accentuation of expiratory times with prolonged expiratory pauses, was markedly different from that induced by CO2 inhalation. Removal of neural input to the central respiratory centers from IPC does not appear to be solely responsible for the altered breathing pattern following vagotomy in birds.

Seventy-five pairs of ovaries from Yankasa Sheep aged 1 1 2 to 3 years were collected from a Zaria abattoir for 12 months, to study the ovarian activity. It was observed that ovarian activity in Yankasa sheep was year-round with maximum activity occurring during the rainy and pre-rain seasons. These periods of maximum ovarian activity might be caused by the availability of pasture during the rainy and pre-rain seasons, since Nigerian sheep obtain most of their food by grazing available pasture.

Ovarian activity of Sokoto red goats was studied for 12 months using 141 pairs of ovaries obtained from a Zaria abattoir. Ovarian activity occurred throughout the year but higher activity was observed during the rainy (June to September) and dry (January to March) seasons. The higher ovarian activity during the rainy season is perhaps due to the availability of pasture during this time, while the higher activity during the dry season might be related to the goat's ability to convert leaves and dry forage that are mostly available during this season into useful nutrients. Temperature increase, particularly during the dry season, might be a factor for higher ovarian activity during the same period.