With 2 figures, 8 tables.

The study was undertaken to investigate the effects of rainy and dry periods on the gross and histological features of ovaries of Oreochromis niloticus in Zaria, Kaduna State, Nigeria. Twenty-four (24) adult wild tilapia fish with average weight of 300.17 ± 25.71 gm and 229.94 ± 23.68 gm was used during rainy and dry periods, respectively. They measured a standard body length of 24.00 ± 0.76 cm and 23.83±0.60 cm during rainy and dry periods, respectively. The fish were sourced from Zaria dam and transported live in open plastic troughs containing clean water to the Gross Anatomy Laboratory, Department of Veterinary Anatomy, Ahmadu Bello University Zaria. Each fish was euthanized using tricaine anaesthetic at 8 drops/litre of water. The ovaries were extracted, weighed and fixed in Bouin’s fluid for 24 hours and processed histologically. Grossly, the ovaries of O. niloticus were highly vascularized and well developed during both rainy and dry periods. The average weight of both ovaries showed insignificant variation across the periods (0.125). The Gonado-somatic index value was insignificantly higher during rainy period (0.115) compared to dry period. Histologically, the ovaries were predominated by vitellogenic and post-vitellogenic follicles across both periods of the year. The tunica albuginea and interstitial connective tissues were thin during both periods. In conclusion, the results in this study revealed that adult wild tilapia fish had developed ovaries with predominant mature follicles during both rainy and dry periods suggesting that adult wild tilapia fish spawns during both rainy and dry periods in Zaria, Nigeria. Keywords: Follicles, Gonado-Somatic Index (GSI), Ovaries, Wild tilapia, Zaria dam

Photoperiod is considered to be one of the most effective environmental factor in controlling the reproductive cycle and gonadal maturation in some mammalian species, but very limited information are available on its effects on  reproductive biology of the guinea fowl.  Therein, we  investigated the effects of varying photoperiodic treatments on morpho-biometry of the excurrent duct system of helmeted guinea fowl (Numida meleagris).  A total of twenty-one (21) apparently healthy sexually-matured helmeted guinea fowls were randomly assigned into three (3) photoperiodic regimes; mainly [Group I: Short daylight (SD; 8 HL (Hour of light, Group II: Moderate daylight (MD; 12 HL) and Group III: Long daylight (LD; 16 HL)] of seven birds per group (n=7). After 8 weeks of experimentation, the excurrent ducts were excised and freed of all adhering connective tissues for gross-morphological and morphometric evaluations. The bio-morphometric data (weight and diameter) were significantly increased (p< 0.05) in the epididymis and ductus deferens of guinea fowl exposed to 16 HL, as compared to other treatments. However, no significant (p> 0.05) effect was observed in body weight and length of the excurrent ducts regardless of photoperiod.    The observed changes in weight and diameter of the epididymis and ductus deferens of helmeted guinea fowl are thus a consequence of the stimulatory effects of long photoperiod exposure to reproductive activity. Thus, these findings would therefore be useful to guinea fowl breeders in designing appropriate intervention programs necessary to improve their  reproduction efficacy and to preserve this species.

With 4 figures and 1 table.

T HE study was undertaken to investigate the histological and functional relationships between the pons and Medulla Oblongata of African Striped Ground Squirrel (Xerus erythropus). Twenty (20) adult African striped ground squirrels were divided in to two groups: 10 males and 10 females. The ground squirrels were obtained from the surrounding villages of Zaria Local Government, Kaduna State Nigeria. Each Squirrel was euthanized using ketamine hydrochloride at dose 80mg/kg BW followed by gentle perfusion with neutral formal saline. A pair of scissors, chisel and scalpel blade was used to gently extract the brain (craniotomy). The extracted brain was fixed in bouins solution for 24hours and processed histologically. The pons and medulla are composed of conspicuous nucleus abducens, nucleus facialis and nucleus trigeminal. The nucleus facialis was found dorsal to the paramedian pontine reticular formation as group of large multipolar neurons. A conspicuous nucleus abducens was found as clusters of medium neurons located lateral to the trigeminal nucleus. In myelencephalon, the cuneate fascicles, intermediate sulcus and lateral sulcus were not evident on dorsal surface but there were grossly visible pyramids and olivary prominence on the ventral surface. Similarly, the nucleus olivary were prominent, nucleus cochlearis and spinal nucleus trigemini were well developed, nucleus hypoglossi, raphe obscurus, lateral reticular nucleus, gigantocellular reticular nucleus were all very distinct. In conclusion, the presence of distinct nuclei in the pons and medulla oblongata gives squirrels fine voluntary skills with good motor coordination and balance and good visual acuity for improved diurnal adaptation.