January 8, 2020 - O. angasi Histology Papers Part 2 and Gonad Sex/Stage Identification Practice

Lab Work

O. angasi histology papers

After talking with Laura yesterday, it seems like she sticks to the format from the da Silva et al. paper (Differences in gametogenic cycle among strains of the European flat oyster Ostrea edulis and relationship between gametogenesis and bonamiosis) when determining gonad sex and stage since this paper takes into account both the stage of the male and female gonads separately when considering hermaphroditic individuals. Thus, I am looking more deeply into this paper today as well as the example images that it offers in order to have a deeper understanding of how to determine gonad sex and age. I am also referring to the example images offered in the Oates paper (OBERVATIONS OF GONAD STRUCTURE AND GAMETOGENIC TIMING IN A RECOVERING POPULATION OF OSTREA LURIDA (CARPENTER 1864)) since is also bases its gonad sex and stage determination off of the da Silva et al. paper.

Gonad Sex/Stage Identification Practice & Observations

  1. Gonad Sex determination

    a. In color images, the female gonad is a bright pink color and the male gonad is a very dark purple.

    b. In monochrome images, the female gonad is gray and the male gonad is a black.

    c. The indeterminate phase is seen in both color and monochrome images as have a lot of white space in the image and no signs of the pink/gray or dark purple/black colors signifying the presence of female and male gonads.

    d. It is slightly easier to identify female and male gonads in color images, but regardless, this drastic color difference makes it simple to identify what gonad sex is being shown (indeterminate, female solely, male solely, hermaphrodite with both sexes equally represented, hermaphrodite predominantly male, and hermaphrodite predominantly female).

  2. Gonad Stage determination

    a. Some general observations that I noticed when practicing gonad stage determination:

    • For male gonads: spermatogonia seem to be in a lighter shade of purple/gray than the later stages of spermatogenesis(spermatocyte balls, spermatids, etc…). Also, as the cells transition further through meiosis (e.g. from spermatogonia to spermatocyte), they become a lot smaller and darker in color. The last stage, which is the spermatozoa balls, just look like big, dark clusters, which is most likely due to the fact that the individual spermatozoa are too small to be individually identifiable.
    • For female gonads: As gametogenesis progresses to the point where the gonad is ripe, the pink cells get progessively larger and tightly packed.
    • For both male and female gonads: for images with partially spawned gonads, it looks similar to the images showing advanced gametogenesis, except that there is a lot more white space.

    b. I found that determining gonad stage is much more difficult than determining gonad sex, especially when the image is of a hermaphroditic individual (since you have to take into consideration both the stage of the male as well as the stage of the female gonad separately). This is something that I think I will have to work on extensively to improve in the future.

Next Steps

  1. Continue practicing gonad sex and gonad stage determination
  2. Go over gonad sex and gonad stage determination with Laura as well as how to measure eggs for gonad stage specificity
Written on January 9, 2020