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We have identified the enteric neuron types expressing immunoreactivity for the calcium-binding protein calbindin D28k (CALB) in cryostat sections and whole-mount preparations of myenteric (MP) and submucosal (SMP) plexuses of sheep ileum. We wished to determine whether CALB-IR in the sheep enteric nervous system was expressed in Dogiel type II cells, as in guinea-pig and rat ileum, and could therefore be used as a marker for intrinsic primary afferent neurons. The neurochemical coding of CALB-containing myenteric and submucosal neurons in ileum of unweaned lamb and mature sheep and its co-localisation with various neural markers was studied immunohistochemically. An antiserum against neuronal nuclear protein (NeuN) failed to detect the entire neuronal population; it was expressed only in 48% of neuron-specific enolase (NSE)-immunoreactive (NSE-IR) neurons. Human neuronal protein appeared to occur in the large majority or all neurons. Almost all CALB-IR neurons were: (1) radially multidendritic; (2) eccentric multidendritic; (3) Dogiel type II. CALB-IR occurred in 20-25% of myenteric and 65-75% of submucosal neurons in lamb and mature sheep, with higher values in mature sheep. Nearly all CALB-IR neurons were common choline acetyltransferase (cChAT)-IR, whereas only about 20% of cChAT-IR somata were CALB-IR. In lamb and mature sheep, 90% of MP CALB-IR neurons were peripheral choline acetyltransferase (pChAT)-IR. In lamb SMP, 80+/-13% of CALB-IR cells were also pChAT-IR, whereas all those in mature SMP were pChAT-IR. Fewer myenteric CALB-IR neurons exhibited tachykinin (TK) in mature sheep (49%) than in lamb (88%). This was also the case for submucosal ganglia (mature sheep, 63%; lamb, 89%). In lamb MP, 77+/-7% of CALB-IR cells were NeuN-positive. In mature sheep, 73+/-10% of CALB-IR somata were NeuN-IR, but NeuN failed to stain SMP neurons. In the MP of suckling and mature sheep, Dogiel type II CALB-IR neurons were calcitonin gene-related peptide (CGRP)-IR. In the SMP at both stages, Dogiel type II CALB-IR somata (about 50% of CALB-IR neurons) were also CGRP-IR. Only small proportions of CALB-IR neurons showed immunoreactivity for calretinin or nitric oxide synthase (NOS), although large populations of CALB and NOS neurons occurred in the ganglia. Thus, CALB is a marker of most Dogiel type II neurons in the sheep but is not confined to Dogiel II neurons. CGRP is a more selective marker of Dogiel type II neurons, being only found in this neuron type.

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Effects of pregnancy stimulation upon histochemically assessed myofibrillar ATPase and muscle fiber diameters were analysed in the rectus abdominis (RA) muscle of guinea pig. Samples of the muscle were taken at 30, 40, 50, 60, and 70 days of pregnancy and compared with samples of the same muscle taken from nonpregnant guinea pigs. Changes in muscle fiber proportions were noted through the course of pregnancy. Starting from 50 days of gestation an increase in type I fibers and a decrease in type IIB fibers were noted. Increase in muscle fiber diameters was also observed in type I, IIA, and IIB fibers. In addition, the RA muscle of the male guinea pig was compared with that of the female guinea pig and showed more type IIA and less type IIB fibers and all the three fiber types were larger than those of the female.