Macro-anatomical and morphometric studies of the hindlimb of grasscutter (Thryonomys swinderianus, Temminck-1827).

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.

Nuclear Architecture in the Medulla Oblongata of the Adult African Giant Pouched Rat (Cricetomys gambianus, Waterhouse - 1840) / Arquitectura Nuclear en la Médula Oblonga de la Rata Gigante de Carillos Africana Adulta (Cricetomys gambianus, Waterhouse - 1840)

The architecture of cranial and non-cranial nerve nuclei in the medulla oblongata of the African giant pouched rat was studied by means of light microscopy. Serial sections of the medulla oblongata, in coronal and saggital planes, were stained with the cresyl fast violet and silver stains, respectively. Sections in the saggital plane were used as a guide, while coronal sections were used to identify the nuclei in the rostrocaudal extent of the medulla oblongata. With the obex serving as the landmark, nuclei rostral and caudal to the obex were delineated. Cranial nerve nuclei whose architecture were defined were the motor nucleus of hypoglossal nerve, motor nucleus of vagus nerve, cochlear nucleus, vestibular nucleus and nucleus ambiguus, while non-cranial nerve nuclei identified were the olivary nucleus, solitary tract nucleus, gracile nucleus, cuneate nucleus, spinal nucleus of trigeminal nerve, motor nucleus of corpus trapezoideum, lateral nucleus of reticular formation and gigantocellular nucleus. The olivary nucleus was the most prominent nucleus, while the solitary tract nucleus was faint, and thus, less developed. The rostrocaudal extent of the solitary tract nucleus, olivary nucleus and motor nucleus of hypoglossal nerve were 3.81 mm, 2.36 mm and 3.50 mm in length, respectively. The prominent olivary nucleus, pyramidal tract and vestibular nucleus are indicative of a good motor coordination and balance, while the poorly developed solitary tract nucleus points to less efficient autonomic functions in this rodent. The present study will serve as a lead for future neuro-behavioural studies necessary for an effective domestication and adaptation of the African giant pouched rat.

Se estudió mediante microscopía de luz la arquitectura de los núcleos de los nervios craneales y no craneales en la médula oblonga de la rata gigante de carillos africana. Secciones seriales de la médula oblonga, en los planos coronal y sagital, se tiñeron con violeta de cresil rápida y tinción de plata, respectivamente. Como guías se utilizaron secciones en el plano sagital, mientras que, secciones coronales se utilizaron para identificar los núcleos en la extensión rostrocaudal de la médula oblonga. Fueron delineados, con el óbex que actúa como punto de referencia, los núcleos rostral y caudal a éste. Los núcleos de los nervios craneales cuya arquitectura se definió fueron los núcleos: motor del nervio hipogloso, motor del nervio vago, coclear, vestibulares y ambiguo, mientras que los núcleos de los nervios craneales no identificados fueron: olivar, del tracto solitario, grácil, cuneiforme, espinal del nervio trigémino, motor del cuerpo trapezoide, lateral de la formación reticular y gigantocelular. El núcleo olivar fue el más importante, mientras que el núcleo del tracto solitario fue tenue, y por lo tanto, menos desarrollado. Las longitud rostrocaudal de los núcleos del tracto solitario, olivar y motor del nervio hipogloso fueron 3,81 mm, 2,36 mm y 3,50 mm, respectivamente. El núcleo prominente olivar, el tracto piramidal y el núcleo vestibular fueron indicativos de una buena coordinación motora y equilibrio, mientras que el escaso desarrollo de los puntos del núcleo del tracto solitario indican una menor eficiencia de las funciones autonómicas en este roedor. El presente estudio servirá para conducir futuros estudios sobre el neuro-comportamiento necesario para una efectiva domesticación y adaptación de la rata gigante de carillos africana adulta.

Sexual dimorphism in the whole brain and brainstem morphometry in the African giant pouched rat (Cricetomys gambianus, Waterhouse 1840).

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.

Time of appearance of esterase-positive alveolar macrophages in bovine fetal lung.

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.

Ovarian activity of Yankasa Sheep using abattoir specimens.

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 using abattoir specimens.

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.

Breathing pattern in anesthetized chickens: CO2 inhalation and vagotomy.

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.