PERINATAL HISTOLOGY OF ENDOCRINE PANCREAS IN ALBINO RAT AN EXPERIMENTAL STUDY

Abstract

Objective: To analyze the process of growth, differentiation and development of pancreatic islet
alpha and beta cells during late fetal and early post-natal period.
Methods: An observational experimental study was conducted in the animal research
laboratories of University of Health Sciences, Lahore. Adult non-diabetic male and female albino
rats were procured from National Institute of Health, Islamabad and kept under standard
conditions in animal house. Mating was allowed by keeping female and male rats in the same
cage with ratio of 3:1. Pregnancy was confirmed by the observation of vaginal plug. Pregnant rats
were divided into 3 groups. First group rats were sacrificed on day 20 of gestation and their
foetuses were dissected to procure the pancreatica of Study group A. Pups were born after 22-23
days postcoitum for rest of the pregnant rats. They were divided into two groups B &C, having ten
pups each. Group B pups were sacrificed on day 2 postnatal and group C on day 7 postnatal to
obtain pancreatic tissue. The pancreatica, so obtained were fixed, processed and sectioned at
4μm thickness. Sections were stained with H&E for light microscopy and with Chrome Alum
Hematoxylin-Phloxin stain for differential counts. Observations were made regarding number of
islets/section, mean diameter of islets, mean number of total cells /islet, mean number of α cell
and β cell/ islet and the mean ratio of β: α cell.
Results: The pancreatic tissue on light microscopy showed both exocrine and endocrine
elements; the former predominated later. Islets of Langerhans were observed as clumps of light
staining cells in well-developed acinar parenchyma in both fetal and postnatal groups; Both
postnatal groups showed strong association of pancreatic tissue with ducts whereas, group A
showed mesenchymal tissue in close vicinity of developing islets. Quantitative variables were
compared using one way ANOVA. Mean islets per section for group A was 6.3±1, for group B
7.8±1 and for group C 3.1 with significant difference among the groups (p<0.05). Mean diameter
of an islet was 112±1 for group A, 136±2 for group B, and 171±5 for group C with statistically
significant difference among the groups. Total number of cells per islet did not show statistically
significant difference (p>0.05). Number of β cells per islet was 95±2 for group A, 76±4 for group B
and 102±3 for group C, which was statistically significant (p<0.05). Number of α cell per islet and
the ratio of β and α cell was not statistically significant among the groups.
Conclusion: All the parameters studied showed gradual increase postnatally. Number of islets
though decreased but the diameter of islets increased gradually. Differential cell counts showed
gradual increase in number with their relative proportion comparable to adult ratios in late
postnatal group