Study on cranial and caudal mesenteric arteries in opossum (Didelphis albiventris) / Estudio de las arterias mesentéricas craneal y caudal del zorrillo (Didelphis albiventris)

The objective of this study is to describe the cranial and caudal mesenteric arteries in 10 opossuns after Neoprene latex injection. The cranial mesenteric artery arises from the abdominal aorta, caudally to the celiac trunk, originating the caudal duodenal pancreatic artery, middle and right colic, jejunal and ileocecocolic arteries. The caudal mesenteric artery arises from the aorta, cranially to the external iliac arteries, originating the cranial rectal and left colic arteries.

El objetivo de este estudio fue describir las arterias mesentéricas craneal y caudal de 10 zorrillos después de la inyección de látex Neoprene. La arteria mesentérica craneal tiene origen en la aorta abdominal, caudalmente al tronco celíaco y da origen a las arterias: pacreáticoduodenal caudal, cólica media derecha, yeyunales e ileocecocólica. La arteria mesentérica caudal con origen en la aorta, cranealmente a las arterias ilíacas externas, da origen a las arterias rectal craneal y cólica izquierda.

Occurrence of amitotic division of trophoblast cell nuclei in blastocysts of the western spotted skunk (Spilogale putorius latifrons).

A cytogenetic examination of spreaded cells of diapausing and early activated blastocysts obtained from 7 female western spotted skunks was performed. Mitosis was not observed in 1626 cells obtained from 9 diapausing blastocysts; however, 12 (1.5%) figures of diploid mitosis were seen in 851 cells from 5 early activated embryos. Diameter of the cell nuclei varied from 4 to 29 microm during diapause, and from 5 to 40 microm in activated blastocyst, and the heterogeneity in nuclear size was significantly different between diapausing and activated embryos (P<0.01). About 80% of nuclei from diapausing blastocysts measured 9 to 16 microm, whereas a similar percentage of nuclei from activated blastocysts ranged from 15 to 27 microm. Many enlarged nuclei exhibited morphological features characteristic of mammalian polytene (i.e. endopolyploid with polytenic organization of chromosomes) trophoblast cells. The number of silver stained nucleoli in all the nuclei did not exceed 2, which corresponds to the number of nucleolus organizers in the diploid karyotype in this species of skunk and suggests the polytene organization of chromosomes in enlarged nuclei. About 10% of large interphase nuclei were observed to undergo amitosis, i.e. direct division by constriction. The resulting nuclear fragments in diapausing blastocysts usually had normal morphology and active nucleoli. In activated embryos, nearly 15% of amitotically divided nuclei appeared to be dividing into fragments of unequal size, one of which had normal cell nuclear morphology and extremely large silver positive nucleoli, and the other fragment exhibited signs of cell death. We interpret these data as indicating that 1) amitotic division of trophoblast endopolyploid cell nuclei in the skunk blastocysts may generate new trophoblast cells which contribute to increased cell number during both diapause and activation stages, and 2) activation of blastocysts after diapause is related to the production of trophoblast cells with enhanced synthetic capabilities.