pubmed.ncbi.nlm.nih.gov

Spectacular alterations in the female reproductive system during the ovarian cycle and adaptations for matrotrophy in chernetid pseudoscorpions (Pseudoscorpiones: Chernetidae) - PubMed

  • ️Sat Jan 01 2022

Spectacular alterations in the female reproductive system during the ovarian cycle and adaptations for matrotrophy in chernetid pseudoscorpions (Pseudoscorpiones: Chernetidae)

Arnold Garbiec et al. Sci Rep. 2022.

Abstract

Pseudoscorpions are small matrotrophic chelicerates. The embryos develop in a brood sac and feed on the nutritive fluid provided by the female. It was widely accepted that the nutritive fluid is synthesized in the ovary. Recent studies have shown that in Chelifer cancroides, a representative of Cheliferidae, considered one of the most derived pseudoscorpion families, the nutritive fluid is produced not only in the ovary but also in the oviducts. Since evolution of adaptations for matrotrophy in pseudoscorpions is poorly known, we aimed to verify our hypothesis that pseudoscorpions of the family Chernetidae, closely related to Cheliferidae, share the traits of adaptations to matrotrophy in the structure and function of the female reproductive system with C. cancroides. We analysed the structure of the ovary and oviducts in five representatives of chernetids with light, confocal, and transmission electron microscopy. The results confirmed our hypothesis and provided new data which broaden our knowledge of matrotrophic pseudoscorpions. We show that in chernetids, the ovary and oviducts undergo significant alterations including their size, multistep hypertrophy and polyploidization of the epithelial cells involved in secretion of the nutritive fluid, the complex secretory activity of the epithelial cells, massive degeneration of the epithelial cells that have completed secretion, and epithelium renewal.

© 2022. The Author(s).

PubMed Disclaimer

Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1

Morphology of the ovaries and oviducts in oogenic phase of the ovarian cycle in Allochernes wideri (A), Chernes hahnii (B), Pselaphochernes lacertosus (C) and Pselaphochernes scorpioides (D). (A–D) Each ovary consists of the ovarian wall and oocytes at different stages of previtellogenic and vitellogenic growth located on the ovary surface. Anteriorly ovaries are connected with paired oviducts. In (B) note the oocyte located on the surface of the oviduct. (A–D) Confocal image of wholemount preparation stained with DAPI (4ʹ,6diamidino-2phenylindole dihydrochloride) (blue fluorescence), and Texas-Red-X Agglutinin (red fluorescence). epOo, early previtellogenic oocyte; od, oviduct; ow, ovarian wall; pOo, previtellogenic oocyte; s, stalk; vOo, vitellogenic oocyte.

Figure 2
Figure 2

Morphology of the ovary in different stages of the oogenic phase in Chernes hahnii (A), Lamprochernes sp. (B) and Allochernes wideri (C,D). (A,B) In the early stages of the oogenic phase, the early previtellogenic oocytes are located in the ovarian wall, and mid- and advanced previtellogenic oocytes protrude on the ovary surface. In mid-previtellogenesis, the ooplasm contains aggregates of organelles and first lipid droplets, while in advanced previtellogenesis, the voluminous lipid droplets predominate. With the progress of previtellogenic growth, the oocyte stalks become longer due to a growing number of the stalk cells, and the follicular cells become arranged meridional on the oocytes surface with nuclei located near the oocyte proximal pole. The stalk cells and the ovarian wall cells are small and alike. The regressed postovulatory stalks located on the ovary surface indicate that the female undergoes the next round of the ovarian cycle. (C,D) In the late stages of the oogenic phase, a part of the oocytes bulged on the ovary surface undergoes vitellogenesis. The oocyte nucleus of vitellogenic oocyte is shifted to the peripheral part. The ooplasm is filled with numerous and voluminous lipid droplets and small number of tiny yolk spheres. Stalk cells and epithelial cells of the ovarian wall are hypertrophic and polyploid. The stalk gains the lumen. The cytoplasm of the stalk cells and follicular cells show a positive signal for ER-Tracker staining (D). (A,C) Semi-thin sections stained with methylene blue. (B) Confocal image of wholemount preparation stained with DAPI (4ʹ,6diamidino-2phenylindole dihydrochloride) (blue fluorescence), and Texas-Red-X Agglutinin (red fluorescence). (D) Confocal image of wholemount preparation stained with DAPI (4ʹ,6diamidino-2phenylindole dihydrochloride) (blue fluorescence), and ER Tracker Red (red fluorescence). ao, aggregates of organelles; apOo, advanced previtellogenic oocyte; bl, basal lamina; epOo, early previtellogenic oocyte; fc, follicular cell; fcn, follicular cell nucleus; ld, lipid droplet; lvOo, late vitellogenic oocyte; mpOo, mid-previtellogenic oocyte; N, oocyte nucleus; Oo, oocyte; ow, ovarian wall; owc, ovarian wall cell; rs, regressed postovulatory stalks; s, stalk; scn, stalk cell nucleus; sl, stalk lumen.

Figure 3
Figure 3

Morphology of the ovary and oviducts in the early stage of the secretory phase (following ovulation) in Allochernes wideri (A–C,F) and Chernes hahnii (D,E). (A–F) In the secretory phase the ovary and oviducts (A,B) considerably increase in size. In the ovary, the postovulatory stalks predominate (A,D), which became several times bigger than the stalks of the oocytes stopped in previtellogenesis (D,E). The postovulatory stalk cells and the epithelial cells of the ovarian wall and the oviducts are highly hypertrophic and polyploid. The cytoplasm of the postovulatory stalk cells and the epithelial cells of the ovarian wall is tightly packed with secretory granules and lipid droplets (B,C, and upper inset). The early previtellogenic oocytes are located on the surface of the hypertrophic epithelial cells of the ovarian wall. In their closest vicinity, small (non-polyploid) somatic cells are denoted by arrows (B). The apical parts of the postovulatory stalk cells start to be detached and enter the lumen of the stalk (C, lower inset). In the next stage (F) the stalk cells of the postovulatory stalk are lower and have secreted a part of secretory granules. Their lumen is filled with the nutritive fluid which stains light blue. (A) Whole mount preparation viewed in Nomarsky optics. (B,C,F) Semi-thin sections stained with methylene blue. (D,E) Confocal image of wholemount preparation stained with DAPI (4ʹ,6diamidino-2phenylindole dihydrochloride) (blue fluorescence), and Texas-Red-X Agglutinin (red fluorescence). ap, apical part of epithelial cell; epOo, early previtellogenic oocyte; fc, follicular cell; L, lumen; ld, lipid droplet; N, oocyte nucleus; nf, nutritive fluid; od, oviduct; ow, ovarian wall; pn, polyploid nucleus; pOo, previtellogenic oocyte; ps, post-ovulatory stalk; s, stalk; sgd, dark secretory granules; sgl, light secretory granules.

Figure 4
Figure 4

Morphology of the ovary and oviducts in the late secretory phase in Pselaphochernes lacertosus (A–D) and Allochernes wideri (E–G). (A–G) During advanced secretory phase the volume of the gonad and the oviducts is increased. The oocytes stopped in previtellogenic or early vitellogenic growth are located close to the ovarian wall among the regressed postovulatory stalks that remained after the previous secretory phase (A, and inset, C). The postovulatory stalks are swollen and voluminous (A,C). The cells of postovulatory stalks and epithelial cells of the ovarian wall are flat with flattened polyploid nuclei (B,D,F,G). The lumen of the latter stalks and the lumen of the ovary is filled with the nutritive fluid which stains dark blue. (A,B) Whole mount preparation viewed in Nomarsky optics. (C,D) Confocal image of wholemount preparation stained with DAPI (4ʹ,6diamidino-2phenylindole dihydrochloride) (blue fluorescence), and Texas-Red-X Agglutinin (red fluorescence). (E–G) Semi-thin sections stained with methylene blue. fcn, follicular cell nucleus; nf, nutritive fluid; od, oviduct; ow, ovarian wall; pOo, previtellogenic oocyte; ps, postovulatory stalk; rs, regressed postovulatory stalks; scpn, stalk cell polyploid nucleus; vOo, vitellogenic oocyte; wcpn, ovarian wall polyploid cell nucleus.

Figure 5
Figure 5

Diagram illustrating changes in the morphology of the stalks and the ovarian epithelium before (A–C) and after (D–F) ovulation (not to scale). For simplicity, the epithelium of the oviduct, which undergoes similar changes to the ovarian epithelium, and the musculature of the ovary and oviducts are not shown. (A) Early oogenic phase. Early previtellogenic oocyte bulges from the ovarian wall covered by follicular cells. The stalk consists of a few cells. (B) Advanced oogenic phase. Advanced previtellogenic/early vitellogenic oocyte is surrounded by follicular cells whose nuclei are located at the oocyte proximal pole. The oocyte stalk is built of several roughly cuboidal cells similar to the epithelial wall cells. (C) Late oogenic phase. Late vitellogenic oocyte is exposed to the body cavity. The oocyte stalk and the ovarian epithelium consist of hypertrophic columnar and polyploid cells. (D) Early secretory phase. The postovulatory stalk and the ovarian epithelium consist of highly hypertrophic and polyploid cells whose cytoplasm is occupied by numerous secretory granules. (E) Advanced secretory phase. The wall of the postovulatory stalk and the ovarian epithelium is built of the polyploid cells that have secreted most of their cytoplasmic content to the lumen of the stalk and the ovary. The nutritive fluid fills the lumen of the stalk and the ovary. (F) Late secretory (regeneration) phase. After secretion of the nutritive fluid, the polyploid epithelial cells of the ovarian wall degenerate and delaminate from the epithelium. The ovarian epithelium is replaced by mitotically active non-polyploid epithelial cells. The postovulatory stalk shrinks and remains on the ovary surface during consecutive ovarian cycles as the regressed postovulatory stalk. fc, follicular cell; mi, mitotic cell division; N, oocyte nucleus; nf, nutritive fluid; Oo, oocyte; ow, ovarian wall; pcr, polyploid cell remnants; ps, post-ovulatory stalk; rs, regressed postovulatory stalk; s, stalk; sg, secretory granules.

Figure 6
Figure 6

Morphology of the oviducts of Chernes hahnii during secretory stage (A–C) and oogenic stage (insets). (A–C) In oogenic stage of the ovarian cycle the wall of the oviduct consists of small and elongated epithelial cells covered by a tight network of striated muscles arranged longitudinally. In the secretory phase the epithelial cells are considerably bigger, with large polyploid nuclei. The external muscle cover is clearly extended. (A–C) Confocal image of wholemount preparation stained with DAPI (4ʹ,6diamidino-2phenylindole dihydrochloride) (blue fluorescence), Alexa Fluor 488 Phalloidin (green fluorescence) and Texas-Red-X Agglutinin (red fluorescence). ms, muscle fibre; odn, oviduct cell nucleus; odpn, oviduct cell polyploid nucleus.

Figure 7
Figure 7

Summarized changes of the morphology of the ovaries and oviducts in Allochernes wideri (A–D), Chernes hahnii (E–H), and Pselaphochernes lacertosus (I–M) during consecutive stages of the ovarian cycle. Photos (A,E,I,J) show ovaries in oogenic stage, photos (B,C,F,G,K,L) in the secretory stage, photos (D,H,M) during regeneration after the secretory stage. Pairs of photos (K,N), (L,O), (M,P) show ovaries and embryos in the corresponding stage. (A–P) Dark-field microscope. nf, nutritive fluid; od, oviduct; Oo, oocyte; po, pumping organ; ps, postovulatory stalk; rs, regressed postovulatory stalk.

Figure 8
Figure 8

Ultrastructure of the preovulatory (A,B) and postovulatory (C,D) stalk cells in Allochernes wideri. (A) In the early oogenic phase the stalk cells which form the stalk of previtellogenic oocyte are cuboidal with small number of organelles. (B) In advances oogenic phase the stalk of the early vitellogenic oocyte is composed of columnar stalk cells with numerous organelles including endoplasmic reticulum, mitochondria, Golgi complexes, and small secretory vesicles. The nuclei of stalk cells are enlarged. (C,D) In the late secretory phase the stalk cells have a reduced hight. Their cytoplasm contains a small number of secretory granules and lipid droplets. The polyploid nuclei are elongated and oriented longitudinal to the basal pole. The lumen of the stalks is filled with nutritive fluid of moderate or electron-dense structure. In the fluid lipid droplets are noticeable close to the apical parts of the stalk cells. (A–D) TEM. (A,B,D insets) Semi-thin sections stained with methylene blue. ER, endoplasmic reticulum; fc, follicular cell; fcn, follicular cell nucleus; Gc, Golgi complexes; ld, lipid droplet; m, mitochondria; nf, nutritive fluid; Oo, oocyte; s, stalk; sc, stalk cell; scn, stalk cell nucleus; scpn, stalk cell polyploid nucleus; sg, secretory granules.

Figure 9
Figure 9

Structure of the ovary (A,C,D) and oviduct (B) of Chernes hahnii during regeneration after the secretory stage. (A–D) After completion of secretion of the nutritive fluid, the epithelial cells of the ovarian and oviductal wall degenerate and delaminate from the epithelium. Their polyploid nuclei and remnants of cytoplasm appear in the lumina of the organs (asterisk). Their place is taken by a new population of epithelial cells that do not show traits of hypertrophy and polyploidization. The postovulatory stalks shrink and remain exposed on the surface of the ovary covered by the folded basal lamina. A part of the cytoplasm content of the stalk cells is released to the lumen of the ovary (arrow). Among degenerating cells mitotically dividing cell is visible. (A–D) Semi-thin sections stained with methylene blue. bl, basal lamina; L, ovarian lumen; ld, lipid dropled; mc, muscle cell; mi, mitotic cell division; odn, oviduct cell nucleus; odpn, oviduct cell polyploid nucleus; own, ovarian wall cell nucleus; owpn, ovarian wall cell polyploid nucleus; rs, regressed postovulatory stalks.

Figure 10
Figure 10

Morphology of the ovary in the third oogenic phase after two ovarian cycles of the Pselaphochernes lacertosus. (A) The ovary contains previtellogenic oocytes growing on the ovary surface, and two types of regressed postovulatory stalks that differ in the size. The smaller regressed postovulatory stalks are the remnants of the postovulatory stalks after completion of the first ovarian cycle, and the bigger ones represent the remnants of the postovulatory stalks of the second ovarian cycle. Inset: The regressed postovulatory stalks after the second ovarian cycle contain stalk cells covered with the highly folded basal lamina. (A) Confocal image of wholemount preparation stained with DAPI (4ʹ,6diamidino-2phenylindole dihydrochloride) (blue fluorescence), and Texas-Red-X Agglutinin (red fluorescence). (inset) Semi-thin section stained with methylene blue. bl, basal lamina; fc, follicular cell; Oo, oocyte; ow, ovarian wall; rs I, regressed postovulatory stalks after first ovarian cycle; rs II, regressed postovulatory stalks after second ovarian cycle; scn, nucleus of the regressed stalk cell; s, stalk.

Similar articles

References

    1. Ostrovsky AN, et al. Matrotrophy and placentation in invertebrates: A new paradigm. Biol. Rev. 2016;91:673–711. doi: 10.1111/brv.12189. - DOI - PMC - PubMed
    1. Blackburn DG. Convergent evolution of viviparity, matrotrophy, and specializations for fetal nutrition in reptiles and other vertebrates. Integr. Comp. Biol. 1992;32:313–321.
    1. Blackburn DG. Evolution of vertebrate viviparity and specializations for fetal nutrition: A quantitative and qualitative analysis. J. Morphol. 2015;276:961–990. doi: 10.1002/jmor.20272. - DOI - PubMed
    1. Riesch R, Plath M, Schlupp I, Marsh-Matthews E. Matrotrophy in the cave molly: An unexpected provisioning strategy in an extreme environment. Evol. Ecol. 2010;24:789–801. doi: 10.1007/s10682-009-9335-z. - DOI
    1. Ostrovsky AN. From incipient to substantial: Evolution of placentotrophy in a phylum of aquatic colonial invertebrates. Evolution. 2013;67:1368–1382. doi: 10.1111/evo.12039. - DOI - PMC - PubMed

Publication types

MeSH terms