Morphological changes in the sexual organs of the pulmonates were observed throughout a year and correlated with reproductive-cycle periods. Reproductive-organ weights of the snail Megalobulimus abbreviatus were recorded seasonally and gonad sections were analyzed morphologically. The weights were used to obtain the organosomatic index. Mean oocytic diameter and oocytic maturation index were based on gonad sections. It was concluded that M. abbreviatus is an iteroparous snail whose annual reproductive cycle is characterized by mating and egg laying throughout spring and early summer, and also by reproductive system preparation, occurring over the remainder of the summer until the end of winter, for a new breeding season.

The effects of anoxic exposure and the post-anoxia aerobic recovery period on carbohydrate metabolism in the central nervous system (CNS) of the land snail Megalobulimus oblongus, an anoxia-tolerant land gastropod, were studied. The snails were exposed to anoxia for periods of 1.5, 3, 6, 12, 18, or 24 hr. In order to study the post-anoxia recovery phase, snails exposed to a 3-hr period of anoxia were returned to aerobic conditions for 1.5, 3, 6, or 15 hr. Glycogen and glucose concentrations in the CNS, hemolymph glucose concentration, and glycogen phosphorylase (active form, GPa) activity in the CNS were analyzed. Anoxia does not significantly affect the concentration of CNS glucose but induces hyperglycemia and a reduction of CNS GPa activity. The glycogen concentration was decreased at 12 hr of anoxia; however, by 18 and 24 hr in anoxia, the glycogen content was not significantly different from basal control values. During the post-anoxia period, the reduction in GPa activity and the increased hemolymph glucose concentration induced by anoxia returned to control values. These results suggest that the CNS of M. oblongus may use hemolymph glucose to fulfill the metabolic demands during anoxia. However, the hypothesis of tissue metabolic arrest cannot be excluded.

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The distribution of the glial cells in the pulmonate gastropod Megalobulimus oblongus was studied by means of an immunohistochemical procedure. These cells expressed glial fibrillary acidic protein in their cell bodies as well as in their processes. In all ganglia of the central nervous system, four types of glial cells were identified. The glial lacunar network and the perineuronal glial cells were found in the cortical region of the ganglia, and the perisynaptic and the fibrous glial cells in the neuropilar region. However, in the procerebrum of the cerebral ganglion the glial cells only had a reticular distribution throughout the cellular area. These observations provide morphological evidence of glial cell functions. These cells are probably involved in the support of neurones, the uptake and/or degradation of neurotransmitters, the transfer of metabolic substrates to neurones, as well as the regulation of ionic constituents of extracellular space. As occurs in vertebrates, there is a strong relationship between the different cellular components of the central nervous system of this invertebrate.