Gliding into diapause: early embryo development in roe deer (Capreolus capreolus)

Abstract

During mammalian diapause, the embryo is arrested at the blastocyst stage. In diapausing carnivores and marsupials, growth arrest of the blastocyst is coincident with a quiescent corpus luteum (CL). In the roe deer, progesterone is produced throughout diapause and the blastocyst exhibits very slow growth. To date, early roe deer embryos of known age have not been described. Therefore, it is not known at which stage and at what pace the roe deer embryo enters diapause. To collect multiple embryos of known gestational age, we performed cycle synchronization and superovulation in captive roe deer prior to artificial insemination (AI) and natural breeding (NB), respectively. Superovulatory responses were evaluated based on ultrasonographic detection of CL formation on the day of in vivo embryo flushing and on plasma progesterone (P4) analysis. In total, 33 superovulation treatments resulted in 6.6  2.2 (mean  SD) CL per doe on the day of embryo flushing. At days 6 and 7 after AI, 37 multicellular embryos up to the morula stage were retrieved from 8 does. At day 12 and 13 after natural breeding, 28 embryos, mainly at the blastocyst stage (n=20), were collected from 7 does. Multiple embryos could be collected from single animals, proving the feasibility of superovulation in this species. Compared to other diapausing and non-diapausing species where blastocysts have formed at days 6 -8, roe deer embryo development appeared to be already decelerated prior to the blastocyst stage. The roe deer might therefore be well suited as a model to investigate mechanisms regulating embryonic growth velocity with respect to cell cycle control.

Amino acids activate mTORC1 to release roe deer embryos from decelerated proliferation during diapause

“…These samples were immediately snap frozen on aluminum foil in liquid nitrogen (−196 °C). Day 13 blastocysts ( n = 6) were derived from captive roe deer by surgical in vivo embryo flushing as described in detail by Drews et al ( 58 ) ( Dataset S3 ). The animal experiment complied with German Animal Welfare law requirements and to the guidelines of the Internal Committee of Ethics and Animal Welfare of the Leibniz Institute for Zoo and Wildlife Research (approval no.…”

“…In vivo collection. Endometrial biopsies and blastocysts were collected mid-August from a group of pregnant captive roe deer at day 13 post-mating by surgical embryo flushing (58). The two surgical access sites for inserting the 8 French Foley collection catheter into the distal part of each uterine horn provided sufficient exposed endometrium before the sites were closed with a single ligation.…”

“…The animal experiment complied with German Animal Welfare law requirements and to the guidelines of the Internal Committee of Ethics and Animal Welfare of the Leibniz Institute for Zoo and Wildlife Research (approval no. 2347-25-2014) (58). Field sampling.…”

Embryonic diapause in mammals and dormancy in embryonic stem cells with the European roe deer as experimental model

“…To date, it remains unknown when and in response to which signal diapause in the roe deer commences. Around Day 14 after fertilisation, expanded blastocysts, hatching and from the zona pellucida completely hatched blastocysts have been found in the uterine horns of roe deer (Drews et al 2020). From early August until late December, the hatched blastocysts remain free floating in the uterus (Lambert et al 2001), exhibiting a comparatively long period of diapause (Renfree and Fenelon 2017).…”