My Apology
To the two emailers and any other reader who was offended by my post “Gonads Wanted” please accept my sincere apology. Thank you for your polite and reasoned words. You hit a Nerve in my brain. I promise I will change my ways.
“Comedy has to be based on truth. You take the truth and you put a little curlicue at the end.”
Sid Caesar
Good Morning Gloucester 
HOW DO WE TELL THE SEX OF THE FISH?
All fish have a pair of reproductive organs called gonads, which produce roe or eggs (females) or smelt or sperm (males). The gonads are located at the top of the gut cavity, just below the fish’s backbone.
In some cases it is possible to determine the sex of a fish just from looking at the colour and shape of the gonad, but often a more detailed examination is required to tell the sex and developmental stage of the fish. This process is known as histology.
The process is quite technical, but it basically involves a few straightforward steps.
Embedding a gonad
Photo: CRC Reef
First, the gonads are removed from the fish and placed in chemicals to preserve the tissues and prevent decay.
Second, slices or sections are cut from the gonad and placed in small blocks of wax to enable ease of handling during processing. These sections are around 5mm thick.
Sectioning a gonad
Photo: CRC Reef
Third, a very thin section is cut from the piece of gonad in the wax block, using a special machine called a microtome – which has a very sharp blade! These sections usually are around 5microns thick (= 0.005mm, or 5-1000ths of a mm) and are mounted on glass slides about 7.5cm long by 2cm wide.
Part of sectioning process
Photo: CRC Reef
Fourth, the section is stained with three different chemical stains to improve the appearance of eggs and sperm when viewed under a microscope. The stains turn different parts of the gonad tissues into different colours and so allow easier identification of the main features of the gonad.
Finally, the thin, stained sections are viewed under a microscope to determine if the fish is a male or a female, or in the process of changing sex.
Section of a ovary (female)
Photo: CRC Reef
Section of a testis (male)
Photo: CRC Reef
What is the big deal about gonads? People in Gloucester have eaten female fish (cod and haddock) gonads for ages. Also refered to as spawn or roe. Go to any Sushi Bar and there are salmon gonads (roe). WT FUDGE
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