Copulation and Successful Insemination by Unfed Amblyomma triguttatum triguttatum Koch

Abstract

all gravid. A detailed study was carried out to determine the reason for absence of eggs in the otherwise mature adult. All specimens were fixed in AFA, stained with Semichon's aceto-carmine and cleared in methyl salicylate. After the anomalous worm was observed and photographed in methyl salicylate, it and two normal specimens were destained, embedded in Paraplast, prepared as 10-Am, transverse, serial sections, and stained with Harris' hematoxylin and eosin. The remaining worms were mounted whole in damar. The two worms from the same host (Figs. 1, 2) were similar in size and both had well-developed gonads. Vitelline cells were dispersed in the parenchyma of the anomalous worm and its transverse vitelline ducts were greatly distended (Fig. 3). Histological sections of the anomalous worm confirmed normal development of the ovary, testes, vitelline follicles, uterus, and seminal receptacle; the latter contained spermatozoa. Oocytes were present in the ovary, oviduct, and ootype but not in the uterus. The uterus contained a small amount of amorphous material but no vitelline cells or shell material. Normal vitelline cells were present in the enlarged vitelavid. A detailed study was carried out to ine the reason for absence of eggs in the line ducts and reservoir and free in the parenchyma, displacing parenchymal tissue (Figs. 4, 5). The ootype appeared normal and open to the oviduct and uterus, but no connection was seen between the vitelline reservoir and oviduct. The role of vitelline cells as a source of eggshell material in trematodes is well known (Smyth and Clegg, 1959, Exp. Parasitol. 8: 286-323). Failure to produce eggs in the present specimen apparently resulted from a blockage or rupture preventing vitelline cells from entering the ootype to release that material. This also explains why the uterus did not contain malformed eggs or shell material as seen in other abnormal trematodes such as those reported by Manter (1927, J. Parasitol. 13: 199-202) and Odlaug (1939, Trans. Am. Microsc. Soc. 58: 67-72). It was not possible to determine whether the anomaly described here resulted from injury to the previously-intact, common vitelline duct or failure of that duct to develop initially; complete absence of vitelline material distal to the vitelline reservoir supports the latter explanation. In either case, the large amount of vitelline material in the parenchyma indicates the abnormality had not been acquired recently.