2026-09-24T10:24:50Zhttps://mro.massey.ac.nz/server/oai/requestoai:mro.massey.ac.nz:10179/59312025-11-11T14:10:29Zcom_10179_294col_10179_296
DSpace at Massey University
author
Ilio, Kenneth Yerro
2014-11-21T02:19:50Z
2014-11-21T02:19:50Z
1983
http://hdl.handle.net/10179/5931
Q112847259
https://www.wikidata.org/wiki/Q112847259
The histology, mitotic index, ultrastructure and
Na+-K+-ATPase cytochemistry of lambs reared on pasture
were studied during the period of weaning.
Two embalmed mature non-pregnant Romney cross-brGd
ewes and thirty Romney-cross lambs reared on Massey
University sheep farms pastures were used. Five lambs
{three in 1981 and two in 1982) were taken from their
dams on pasture at each of the following respective
ages: within 24 hours of birth, and at 12, 23, 34, 45
and 56 days. Stomach-tissue samples from 1 adult and
from the lambs reared during the 1981 lambing season
were prepared for histology using Haenatoxylin and Eosin,
Nasson's green trichrome, Periodic-acid-Schiff and
Toluidine Blue stains, and for conventional transmission
electron microscopy. Tissue samples from the rumens of
lambs reared during the 1982 season were used for
strontium-capture technique Na+-K+-ATPase cytochemistry .
Gross dissection o£ the stomach of one-day-old lambs
confirmed that the largest compartment at birth is the
abomasum, followed, in decreasing order of size; by the
rumen, reticulum and omasum. Progressive development
resulted in the forestomach compartments assuming their
adult proportions by 56 days of age.
Preliminary histological studies of epithelium taken
from the rumen, reticulum, omasum and reticular groove
of the adult sheep c0nfirmed it to be a stratified
keratinizing epithelium. Five general cell layers were
clearly seen: stratum basa1e, stratum spinosum,
stratum granulosum, stratus transiticnale and stratum
corneum. (In previous studies, the stratum granulosun
and the stratum transitionale have been considered as one
layer.) Mucopolysaccharides were located in the inter-
cellular spaces in the stratum corneum.
It is concluded that the ultrastructural features
and Na+-K+-ATPase cytochemistry of the epithelium at 12
days of age appeared to be similar to those found in
older animals. However, structural (and presumably
functional) maturity did not appear to be complete until
after 45 days of age at which stage the stratum transi-
tionale had become complete and the mitotic index and
the thickness of the epithelium had become stable.
The increase of non-keratinocytes suggests the increasing
immunocompetence of the epithelium.
Tight junctions and extruded contents of membrane-
coating granules in the intercellular spaces of the stratum
corneum could provide a barrier to the diffusion of
solutes across the epithelium. The development of gap
junctions and the presence of Na+-K+-ATPase enzymatic
sites in the membranes are consistent with the absorptive
and transport functions of the epithelium, particularly
the active transepithelial movement of sodium ions.
Future studies could well show hormones, hormone-like
substances and antibiotics to be important in the
development of the forestomach epithelium in ruminants.
en
The Author
Lambs
Epithelium
Epithelial development in the forestomach of pasture-fed lambs (birth to 8 weeks) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Veterinary Science at Massey University, New Zealand
Thesis
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