**6. Morphological characterization of trypanosomes**

Morphological features assist in the preliminary identification of trypanosomes in the field after isolation in order to ascertain the species of trypanosomes isolated. This is done through microscopic examination. Different trypanosome species fall into the following groups, depending on the morphological features: Trypanozoon, Duttonella, or Nannomonas (**Table 1**).


**Table 1.** Morphological characteristics of trypanosomes.

#### **6.1. Some of the trypanosome species distinguishing morphological characteristics include:**


The morphological features of the Trypanozoon, Duttonella, and Nannomonas species of trypanosomes are as shown in **Figures 5**–**7**.

**Figure 5.** Morphological distinguishing features associated with Trypanozoon.

**Figure 6.** Morphological distinguishing features associated with Duttonella.

Isolation and Cryopreservation of Trypanosomes and their Vectors for Research and Development in Resource... http://dx.doi.org/10.5772/65283 15

**Figure 7.** Morphological distinguishing features associated with Nannomonas.

#### *6.1.1. Trypanosoma brucei gambiense (Trypanozoon) subgroup*

Morphological distinguishing features associated with Trypanozoon include:


**6.1. Some of the trypanosome species distinguishing morphological characteristics include:**

The morphological features of the Trypanozoon, Duttonella, and Nannomonas species of

**•** The shape of the posterior end which is pointed either sharply, oval, or blunt

**•** Size and shape of the body

14 Cryopreservation in Eukaryotes

**•** Position of the nucleus and kinetoplast

**•** Presence or absence of free flagellum

trypanosomes are as shown in **Figures 5**–**7**.

**Figure 5.** Morphological distinguishing features associated with Trypanozoon.

**Figure 6.** Morphological distinguishing features associated with Duttonella.

**•** Free flagellum—present

#### *6.1.2. Trypanosoma vivax (Duttonella) subgroup*

Distinguishing features include: rounded posterior end, free flagellum, and a large almost terminal kinetoplast. This group of parasites lack undulating membrane.

#### *6.1.3. Trypanosoma simiae in the same group with T. congolense (Nannomonas)*

Distinguishing features include: shape of posterior end—rounded; position of kinetoplast marginal; size of kinetoplast—medium; no undulating membrane and free flagellum present.

#### *6.1.4. Other methods employed in the laboratory to characterize trypanosomes*

**•** Tsetse transmission studies

*Trypanosoma evansi* is not transmitted by *Glossina* but by biting flies.

**•** Tissue culture

*Trypanosoma evansi* does not transform into procyclics in culture.

	- **◦** DNA and RNA extraction and analysis
	- **◦** Genetics and functional genomic studies
